Bump kotlin_version from 2.0.21 to 2.1.0 (#316)

Bumps `kotlin_version` from 2.0.21 to 2.1.0.

Updates `org.jetbrains.kotlin:kotlin-gradle-plugin` from 2.0.21 to 2.1.0
- [Release notes](https://github.com/JetBrains/kotlin/releases)
- [Changelog](https://github.com/JetBrains/kotlin/blob/v2.1.0/ChangeLog.md)
- [Commits](JetBrains/kotlin@v2.0.21...v2.1.0)

Updates `org.jetbrains.kotlin:kotlin-stdlib` from 2.0.21 to 2.1.0
- [Release notes](https://github.com/JetBrains/kotlin/releases)
- [Changelog](https://github.com/JetBrains/kotlin/blob/v2.1.0/ChangeLog.md)
- [Commits](JetBrains/kotlin@v2.0.21...v2.1.0)

---
updated-dependencies:
- dependency-name: org.jetbrains.kotlin:kotlin-gradle-plugin
  dependency-type: direct:production
  update-type: version-update:semver-minor
- dependency-name: org.jetbrains.kotlin:kotlin-stdlib
  dependency-type: direct:production
  update-type: version-update:semver-minor
...

Signed-off-by: dependabot[bot] <[email protected]>
Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>

build.gradle

@@ -1,6 +1,6 @@
 buildscript {
     ext {
-        kotlin_version = '2.0.21'
+        kotlin_version = '2.1.0'
         kotpref_version = '2.13.2'
     }