build(deps): bump kotlin.version from 2.1.20 to 2.1.21

Bumps `kotlin.version` from 2.1.20 to 2.1.21.

Updates `org.jetbrains.kotlin:kotlin-stdlib-jdk8` from 2.1.20 to 2.1.21
- [Release notes](https://github.com/JetBrains/kotlin/releases)
- [Changelog](https://github.com/JetBrains/kotlin/blob/master/ChangeLog.md)
- [Commits](JetBrains/kotlin@v2.1.20...v2.1.21)

Updates `org.jetbrains.kotlin:kotlin-reflect` from 2.1.20 to 2.1.21
- [Release notes](https://github.com/JetBrains/kotlin/releases)
- [Changelog](https://github.com/JetBrains/kotlin/blob/master/ChangeLog.md)
- [Commits](JetBrains/kotlin@v2.1.20...v2.1.21)

Updates `org.jetbrains.kotlin:kotlin-test-junit` from 2.1.20 to 2.1.21
- [Release notes](https://github.com/JetBrains/kotlin/releases)
- [Changelog](https://github.com/JetBrains/kotlin/blob/master/ChangeLog.md)
- [Commits](JetBrains/kotlin@v2.1.20...v2.1.21)

Updates `org.jetbrains.kotlin:kotlin-maven-noarg` from 2.1.20 to 2.1.21

Updates `org.jetbrains.kotlin:kotlin-maven-allopen` from 2.1.20 to 2.1.21

Updates `org.jetbrains.kotlin:kotlin-maven-plugin` from 2.1.20 to 2.1.21

---
updated-dependencies:
- dependency-name: org.jetbrains.kotlin:kotlin-stdlib-jdk8
  dependency-version: 2.1.21
  dependency-type: direct:production
  update-type: version-update:semver-patch
- dependency-name: org.jetbrains.kotlin:kotlin-reflect
  dependency-version: 2.1.21
  dependency-type: direct:production
  update-type: version-update:semver-patch
- dependency-name: org.jetbrains.kotlin:kotlin-test-junit
  dependency-version: 2.1.21
  dependency-type: direct:development
  update-type: version-update:semver-patch
- dependency-name: org.jetbrains.kotlin:kotlin-maven-noarg
  dependency-version: 2.1.21
  dependency-type: direct:production
  update-type: version-update:semver-patch
- dependency-name: org.jetbrains.kotlin:kotlin-maven-allopen
  dependency-version: 2.1.21
  dependency-type: direct:production
  update-type: version-update:semver-patch
- dependency-name: org.jetbrains.kotlin:kotlin-maven-plugin
  dependency-version: 2.1.21
  dependency-type: direct:production
  update-type: version-update:semver-patch
...

Signed-off-by: dependabot[bot] <support@github.com>

Author: dependabot[bot]

pom.xml

@@ -10,7 +10,7 @@
   <properties>
     <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
     <java.version>21</java.version>
-    <kotlin.version>2.1.20</kotlin.version>
+    <kotlin.version>2.1.21</kotlin.version>
     <maven.compiler.source>${java.version}</maven.compiler.source>
     <maven.compiler.target>${java.version}</maven.compiler.target>
     <junit-jupiter.version>5.12.2</junit-jupiter.version>