Bump org.jetbrains.kotlin.jvm from 2.0.20 to 2.0.21 in /kotlin

Bumps [org.jetbrains.kotlin.jvm](https://github.com/JetBrains/kotlin) from 2.0.20 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@v2.0.20...v2.0.21)

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

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

kotlin/build.gradle

@@ -3,7 +3,7 @@ import org.jetbrains.kotlin.gradle.tasks.KotlinCompile
 plugins {
 	id 'org.springframework.boot' version '3.3.4'
 	id 'io.spring.dependency-management' version '1.1.6'
-	id 'org.jetbrains.kotlin.jvm' version '2.0.20'
+	id 'org.jetbrains.kotlin.jvm' version '2.0.21'
 	id 'org.jetbrains.kotlin.plugin.spring' version '2.0.20'
 }