chore(deps): bump kotlin.version from 2.0.20 to 2.0.21 (#784)

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/master/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

---
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
...

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

pom.xml

@@ -122,7 +122,7 @@
         <plugin.scala.version>4.9.2</plugin.scala.version>
 
         <pekko.version>1.1.1</pekko.version>
-        <kotlin.version>2.0.20</kotlin.version>
+        <kotlin.version>2.0.21</kotlin.version>
         <junit-jupiter.version>5.11.1</junit-jupiter.version>
         <kotlin-coroutines.version>1.8.1</kotlin-coroutines.version>
         <mockito.version>4.10.0</mockito.version>