build(deps): bump plugin.serialization from 2.0.21 to 2.1.0

Bumps [plugin.serialization](https://github.com/JetBrains/kotlin) from 2.0.21 to 2.1.0.
- [Release notes](https://github.com/JetBrains/kotlin/releases)
- [Changelog](https://github.com/JetBrains/kotlin/blob/master/ChangeLog.md)
- [Commits](JetBrains/kotlin@v2.0.21...v2.1.0)

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

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

build.gradle.kts

@@ -3,7 +3,7 @@ plugins {
   id("org.jetbrains.kotlin.jvm") version "2.0.21"
   id("org.jetbrains.intellij.platform") version "2.1.0"
 
-  kotlin("plugin.serialization") version "2.0.21"
+  kotlin("plugin.serialization") version "2.1.0"
 }
 
 group = "jp.s6n.idea"