Bump kotlin from 2.2.20 to 2.2.21

Bumps `kotlin` from 2.2.20 to 2.2.21.

Updates `org.jetbrains.kotlin:kotlin-test` from 2.2.20 to 2.2.21
- [Release notes](https://github.com/JetBrains/kotlin/releases)
- [Changelog](https://github.com/JetBrains/kotlin/blob/master/ChangeLog.md)
- [Commits](JetBrains/kotlin@v2.2.20...v2.2.21)

Updates `org.jetbrains.kotlin.multiplatform` from 2.2.20 to 2.2.21
- [Release notes](https://github.com/JetBrains/kotlin/releases)
- [Changelog](https://github.com/JetBrains/kotlin/blob/master/ChangeLog.md)
- [Commits](JetBrains/kotlin@v2.2.20...v2.2.21)

---
updated-dependencies:
- dependency-name: org.jetbrains.kotlin:kotlin-test
  dependency-version: 2.2.21
  dependency-type: direct:production
  update-type: version-update:semver-patch
- dependency-name: org.jetbrains.kotlin.multiplatform
  dependency-version: 2.2.21
  dependency-type: direct:production
  update-type: version-update:semver-patch
...

Signed-off-by: dependabot[bot] <[email protected]>

Author: dependabot[bot]

gradle/libs.versions.toml

@@ -1,6 +1,6 @@
 [versions]
 agp = "8.13.0"
-kotlin = "2.2.20"
+kotlin = "2.2.21"
 android-minSdk = "24"
 android-compileSdk = "36"
 vanniktechMavenPublish = "0.34.0"