chore(deps): bump org.jetbrains.kotlin:kotlin-stdlib-jdk7

Bumps [org.jetbrains.kotlin:kotlin-stdlib-jdk7](https://github.com/JetBrains/kotlin) 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)

---
updated-dependencies:
- dependency-name: org.jetbrains.kotlin:kotlin-stdlib-jdk7
  dependency-type: direct:production
  update-type: version-update:semver-patch
...

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

tutorials/kotlin/Polygons/gradle/libs.versions.toml

@@ -4,7 +4,7 @@ minSdk = "21"
 targetSdk = "34"
 versionCode = "1"
 versionName = "1.0"
-kotlin = "2.0.0"
+kotlin = "2.0.21"
 appcompat = "1.7.0"
 playServicesMaps = "19.0.0"
 junit = "4.13.2"