Bump kotlin from 2.0.0 to 2.0.21 (#909)

Bumps `kotlin` from 2.0.0 to 2.0.21.

Updates `org.jetbrains.kotlin:kotlin-bom` from 2.0.0 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@v2.0.0...v2.0.21)

Updates `org.jetbrains.kotlin:kotlin-stdlib` from 2.0.0 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@v2.0.0...v2.0.21)

Updates `org.jetbrains.kotlin.jvm` from 2.0.0 to 2.0.21

---
updated-dependencies:
- dependency-name: org.jetbrains.kotlin:kotlin-bom
  dependency-type: direct:production
  update-type: version-update:semver-patch
- dependency-name: org.jetbrains.kotlin:kotlin-stdlib
  dependency-type: direct:production
  update-type: version-update:semver-patch
- dependency-name: org.jetbrains.kotlin.jvm
  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>

gradle/libs.versions.toml

@@ -1,5 +1,5 @@
 [versions]
-kotlin = "2.0.0"
+kotlin = "2.0.21"
 
 [plugins]
 dokka = { id = "org.jetbrains.dokka", version = "1.9.20" }