Bump kotlin.version from 2.0.20 to 2.0.21

Bumps `kotlin.version` from 2.0.20 to 2.0.21.

Updates `org.jetbrains.kotlin:kotlin-stdlib` from 2.0.20 to 2.0.21
- [Release notes](https://github.com/JetBrains/kotlin/releases)
- [Changelog](https://github.com/JetBrains/kotlin/blob/v2.0.21/ChangeLog.md)
- [Commits](JetBrains/kotlin@v2.0.20...v2.0.21)

Updates `org.jetbrains.kotlin:kotlin-maven-plugin` from 2.0.20 to 2.0.21

Updates `org.jetbrains.kotlin:kotlin-reflect` from 2.0.20 to 2.0.21
- [Release notes](https://github.com/JetBrains/kotlin/releases)
- [Changelog](https://github.com/JetBrains/kotlin/blob/v2.0.21/ChangeLog.md)
- [Commits](JetBrains/kotlin@v2.0.20...v2.0.21)

---
updated-dependencies:
- dependency-name: org.jetbrains.kotlin:kotlin-stdlib
  dependency-type: direct:production
  update-type: version-update:semver-patch
- dependency-name: org.jetbrains.kotlin:kotlin-maven-plugin
  dependency-type: direct:production
  update-type: version-update:semver-patch
- dependency-name: org.jetbrains.kotlin:kotlin-reflect
  dependency-type: direct:development
  update-type: version-update:semver-patch
...

Signed-off-by: dependabot[bot] <[email protected]>

pom.xml

@@ -18,7 +18,7 @@
         <junit-jupiter.version>5.11.2</junit-jupiter.version>
         <json-path.version>2.9.0</json-path.version>
         <opentest4j.version>1.3.0</opentest4j.version>
-        <kotlin.version>2.0.20</kotlin.version>
+        <kotlin.version>2.0.21</kotlin.version>
         <bnd.version>7.0.0</bnd.version>
         <symbolic.name>${project.groupId}.${project.artifactId}</symbolic.name>
         <osgi.importPackage>!kotlin.*,*</osgi.importPackage>