Bump kotlin from 2.0.21 to 2.3.21 (#41)

Bumps `kotlin` from 2.0.21 to 2.3.21.

Updates `org.jetbrains.kotlin:kotlin-stdlib-jdk8` from 2.0.21 to 2.3.21
- [Release notes](https://github.com/JetBrains/kotlin/releases)
- [Changelog](https://github.com/JetBrains/kotlin/blob/master/ChangeLog.md)
- [Commits](JetBrains/kotlin@v2.0.21...v2.3.21)

Updates `org.jetbrains.kotlin:kotlin-reflect` from 2.0.21 to 2.3.21
- [Release notes](https://github.com/JetBrains/kotlin/releases)
- [Changelog](https://github.com/JetBrains/kotlin/blob/master/ChangeLog.md)
- [Commits](JetBrains/kotlin@v2.0.21...v2.3.21)

Updates `org.jetbrains.kotlin.jvm` from 2.0.21 to 2.3.21
- [Release notes](https://github.com/JetBrains/kotlin/releases)
- [Changelog](https://github.com/JetBrains/kotlin/blob/master/ChangeLog.md)
- [Commits](JetBrains/kotlin@v2.0.21...v2.3.21)

---
updated-dependencies:
- dependency-name: org.jetbrains.kotlin:kotlin-stdlib-jdk8
  dependency-version: 2.3.21
  dependency-type: direct:production
  update-type: version-update:semver-minor
- dependency-name: org.jetbrains.kotlin:kotlin-reflect
  dependency-version: 2.3.21
  dependency-type: direct:production
  update-type: version-update:semver-minor
- dependency-name: org.jetbrains.kotlin.jvm
  dependency-version: 2.3.21
  dependency-type: direct:production
  update-type: version-update:semver-minor
...

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

Author: dependabot[bot]

gradle/libs.versions.toml

@@ -7,7 +7,7 @@ assertJ = "3.27.7"
 googleJavaFormat = "1.35.0"
 # only used in Kotlin sample
 # https://central.sonatype.com/artifact/org.jetbrains.kotlin/kotlin-stdlib-jdk8/versions
-kotlin = "2.0.21"
+kotlin = "2.3.21"
 # https://github.com/facebook/ktfmt/releases/
 ktfmt = "0.62"
 # https://central.sonatype.com/artifact/org.junit.jupiter/junit-jupiter/versions