Bump plugin.serialization from 1.8.10 to 2.0.21

Bumps [plugin.serialization](https://github.com/JetBrains/kotlin) from 1.8.10 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@v1.8.10...v2.0.21)

---
updated-dependencies:
- dependency-name: plugin.serialization
  dependency-type: direct:production
  update-type: version-update:semver-major
...

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

buildSrc/build.gradle.kts

@@ -1,7 +1,7 @@
 plugins {
     `kotlin-dsl`
     kotlin("jvm") version "1.8.10"
-    kotlin("plugin.serialization") version "1.8.10"
+    kotlin("plugin.serialization") version "2.0.21"
 //    id("java-gradle-plugin")
 }