Bump kotlin.version from 1.5.20 to 1.5.21 in /value

Bumps `kotlin.version` from 1.5.20 to 1.5.21.
Updates `kotlin-stdlib` from 1.5.20 to 1.5.21
<details>
<summary>Release notes</summary>
<p><em>Sourced from <a href="https://github.com/JetBrains/kotlin/releases">kotlin-stdlib's releases</a>.</em></p>
<blockquote>
<h2>Kotlin 1.5.21</h2>
<h2>Changelog</h2>
<h3>Compiler</h3>
<ul>
<li><a href="https://youtrack.jetbrains.com/issue/KT-47320"><code>KT-47320</code></a> &quot;StringConcatException: Mismatched number of concat arguments&quot; String concatenation fails when template contains special character</li>
<li><a href="https://youtrack.jetbrains.com/issue/KT-47445"><code>KT-47445</code></a> &quot;definitely not null type parameters is only available since language version 1.6&quot; error in cast expression</li>
<li><a href="https://youtrack.jetbrains.com/issue/KT-47446"><code>KT-47446</code></a> Improve warning message INTEGER_OPERATOR_RESOLVE_WILL_CHANGE</li>
<li><a href="https://youtrack.jetbrains.com/issue/KT-47447"><code>KT-47447</code></a> False positive INTEGER_OPERATOR_RESOLVE_WILL_CHANGE warning: &quot;expression will be resolved to Int in future releases&quot;</li>
<li><a href="https://youtrack.jetbrains.com/issue/KT-47449"><code>KT-47449</code></a> JVM / IR: ClassCastException IrStarProjectionImpl  cannot be cast to IrTypeProjection</li>
<li><a href="https://youtrack.jetbrains.com/issue/KT-47459"><code>KT-47459</code></a> &quot;IndexOutOfBoundsException: Index 0 out of bounds for length 0&quot; caused by MarkertManager dependency</li>
<li><a href="https://youtrack.jetbrains.com/issue/KT-47480"><code>KT-47480</code></a> StackOverflowError: Recursion on erasion of raw type with interdependent type parameters</li>
</ul>
<h3>Tools. Compiler Plugins</h3>
<ul>
<li><a href="https://youtrack.jetbrains.com/issue/KT-47161"><code>KT-47161</code></a> Serializable class can't be inherited from serializable class in other module with: e: org.jetbrains.kotlin.codegen.CompilationException: Back-end (JVM) Internal error: Couldn't transform method node: write$Self</li>
<li><a href="https://youtrack.jetbrains.com/issue/KT-47455"><code>KT-47455</code></a> Kotlin lombok plugin NullPointerException</li>
<li><a href="https://youtrack.jetbrains.com/issue/KT-47513"><code>KT-47513</code></a> Lombok compiler plugin failed with 'Recursion detected in a lazy value under LockBasedStorageManager@1c21db60 (TopDownAnalyzer for JVM)'</li>
</ul>
<h3>Tools. Gradle</h3>
<ul>
<li><a href="https://youtrack.jetbrains.com/issue/KT-47444"><code>KT-47444</code></a> Gradle Plugin: Publishing project with &quot;maven-publish&quot; fails when dependency versions are omitted (NPE in MppDependencyRewritingUtilsKt.associateDependenciesWithActualModuleDependencies)</li>
</ul>
<h3>Tools. kapt</h3>
<ul>
<li><a href="https://youtrack.jetbrains.com/issue/KT-47416"><code>KT-47416</code></a> Kapt Gradle DSL ignores javaCompilerOptions in 1.5.20</li>
</ul>
<h2>Checksums</h2>
<table>
<thead>
<tr>
<th>File</th>
<th>Sha256</th>
</tr>
</thead>
<tbody>
<tr>
<td>kotlin-compiler-1.5.21.zip</td>
<td>f3313afdd6abf1b8c75c6292f4e41f2dbafefc8f6c72762c7ba9b3daeef5da59</td>
</tr>
<tr>
<td>kotlin-native-linux-1.5.21.tar.gz</td>
<td>fa3dfec9c11711c2b713a1482bcc4511bb8f73f182f12aa7d858943f6f084397</td>
</tr>
<tr>
<td>kotlin-native-macos-1.5.21.tar.gz</td>
<td>adced4f332b2d3f91d14bf3cf5c1059cfbbac4dc75d91ae88645118badbc401a</td>
</tr>
<tr>
<td>kotlin-native-windows-1.5.21.zip</td>
<td>9da4f5c2f98ac003a062c5a18260a5ed52154b5506d045539f0f3c1bfadf6b01</td>
</tr>
</tbody>
</table>
</blockquote>
</details>
<details>
<summary>Changelog</summary>
<p><em>Sourced from <a href="https://github.com/JetBrains/kotlin/blob/v1.5.21/ChangeLog.md">kotlin-stdlib's changelog</a>.</em></p>
<blockquote>
<h2>1.5.21</h2>
<h3>Compiler</h3>
<ul>
<li><a href="https://youtrack.jetbrains.com/issue/KT-47320"><code>KT-47320</code></a> &quot;StringConcatException: Mismatched number of concat arguments&quot; String concatenation fails when template contains special character</li>
<li><a href="https://youtrack.jetbrains.com/issue/KT-47445"><code>KT-47445</code></a> &quot;definitely not null type parameters is only available since language version 1.6&quot; error in cast expression</li>
<li><a href="https://youtrack.jetbrains.com/issue/KT-47446"><code>KT-47446</code></a> Improve warning message INTEGER_OPERATOR_RESOLVE_WILL_CHANGE</li>
<li><a href="https://youtrack.jetbrains.com/issue/KT-47447"><code>KT-47447</code></a> False positive INTEGER_OPERATOR_RESOLVE_WILL_CHANGE warning: &quot;expression will be resolved to Int in future releases&quot;</li>
<li><a href="https://youtrack.jetbrains.com/issue/KT-47449"><code>KT-47449</code></a> JVM / IR: ClassCastException IrStarProjectionImpl  cannot be cast to IrTypeProjection</li>
<li><a href="https://youtrack.jetbrains.com/issue/KT-47459"><code>KT-47459</code></a> &quot;IndexOutOfBoundsException: Index 0 out of bounds for length 0&quot; caused by MarkertManager dependency</li>
<li><a href="https://youtrack.jetbrains.com/issue/KT-47480"><code>KT-47480</code></a> StackOverflowError: Recursion on erasion of raw type with interdependent type parameters</li>
</ul>
<h3>Tools. Compiler Plugins</h3>
<ul>
<li><a href="https://youtrack.jetbrains.com/issue/KT-47161"><code>KT-47161</code></a> Serializable class can't be inherited from serializable class in other module with: e: org.jetbrains.kotlin.codegen.CompilationException: Back-end (JVM) Internal error: Couldn't transform method node: write$Self</li>
<li><a href="https://youtrack.jetbrains.com/issue/KT-47455"><code>KT-47455</code></a> Kotlin lombok plugin NullPointerException</li>
<li><a href="https://youtrack.jetbrains.com/issue/KT-47513"><code>KT-47513</code></a> Lombok compiler plugin failed with 'Recursion detected in a lazy value under LockBasedStorageManager@1c21db60 (TopDownAnalyzer for JVM)'</li>
</ul>
<h3>Tools. Gradle</h3>
<ul>
<li><a href="https://youtrack.jetbrains.com/issue/KT-47444"><code>KT-47444</code></a> Gradle Plugin: Publishing project with &quot;maven-publish&quot; fails when dependency versions are omitted (NPE in MppDependencyRewritingUtilsKt.associateDependenciesWithActualModuleDependencies)</li>
</ul>
<h3>Tools. kapt</h3>
<ul>
<li><a href="https://youtrack.jetbrains.com/issue/KT-47416"><code>KT-47416</code></a> Kapt Gradle DSL ignores javaCompilerOptions in 1.5.20</li>
</ul>
</blockquote>
</details>
<details>
<summary>Commits</summary>
<ul>
<li><a href="https://github.com/JetBrains/kotlin/commit/ec9d0b09726ea5d3cf30a4c5679e9b2e83974dcc"><code>ec9d0b0</code></a> Add changelog for 1.5.21</li>
<li><a href="https://github.com/JetBrains/kotlin/commit/f2b67285b45667e91c0cdc30e69c4a84230f99a2"><code>f2b6728</code></a> Add change notes for 1.5.21</li>
<li><a href="https://github.com/JetBrains/kotlin/commit/d9dd7f6126d283ed0325bb75193c112b1c1e026e"><code>d9dd7f6</code></a> IR: repair collectAndFilterRealOverrides</li>
<li><a href="https://github.com/JetBrains/kotlin/commit/70522f6bc4521839f510dea2784c1cb19a0dcd0d"><code>70522f6</code></a> JVM_IR: simplify resolveFakeOverride call in SyntheticAccessorLowering</li>
<li><a href="https://github.com/JetBrains/kotlin/commit/384389399ab8fea8247c9a10cafa4b55fa3b93a2"><code>3843893</code></a> IR: properly compute IrProperty.resolveFakeOverride()</li>
<li><a href="https://github.com/JetBrains/kotlin/commit/a1e6c8732c17c01eeab7535e4c474f88040a0081"><code>a1e6c87</code></a> Fix Gradle tests failing compilation.</li>
<li><a href="https://github.com/JetBrains/kotlin/commit/18328f9f5e62313ddcf1a35205e01bfe4ceb5a85"><code>18328f9</code></a> Create a copy of incorrectly deserialized parent's writeSelf function</li>
<li><a href="https://github.com/JetBrains/kotlin/commit/68474d7666eb94e856f2221f0846784cc1a2c0d6"><code>68474d7</code></a> Fix publication failed in projects which are using BOM.</li>
<li><a href="https://github.com/JetBrains/kotlin/commit/8538ed45ddb2ae097d51f9813466dbcfabebfeb7"><code>8538ed4</code></a> [lombok] Get field names directly from JavaClassImpl</li>
<li><a href="https://github.com/JetBrains/kotlin/commit/26c0b3da9d56d99c2a12cf37b1a1a2e93469bf43"><code>26c0b3d</code></a> [FE 1.0] Fix message of INTEGER_OPERATOR_RESOLVE_WILL_CHANGE warning</li>
<li>Additional commits viewable in <a href="https://github.com/JetBrains/kotlin/compare/v1.5.20...v1.5.21">compare view</a></li>
</ul>
</details>
<br />

Updates `kotlin-maven-plugin` from 1.5.20 to 1.5.21

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</details>

Fixes #1131

COPYBARA_INTEGRATE_REVIEW=#1131 from google:dependabot/maven/value/kotlin.version-1.5.21 98be7f0
PiperOrigin-RevId: 384554054

value/src/it/functional/pom.xml

@@ -32,7 +32,7 @@
   <version>HEAD-SNAPSHOT</version>
   <name>Auto-Value Functional Integration Test</name>
   <properties>
-    <kotlin.version>1.5.20</kotlin.version>
+    <kotlin.version>1.5.21</kotlin.version>
     <exclude.tests>this-matches-nothing</exclude.tests>
   </properties>
   <dependencies>