Bump org.jetbrains.kotlin.plugin.allopen from 1.9.24 to 2.0.21 (#574)

Bumps [org.jetbrains.kotlin.plugin.allopen](https://github.com/JetBrains/kotlin) from 1.9.24 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@v1.9.24...v2.0.21)

---
updated-dependencies:
- dependency-name: org.jetbrains.kotlin.plugin.allopen
  dependency-type: direct:production
  update-type: version-update:semver-major
...

Signed-off-by: dependabot[bot] <[email protected]>
Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>

build.gradle.kts

@@ -30,7 +30,7 @@ val githubPassword: String by project
 plugins {
     kotlin("jvm") version "1.9.24"
     id("java")
-    id("org.jetbrains.kotlin.plugin.allopen") version "1.9.24"
+    id("org.jetbrains.kotlin.plugin.allopen") version "2.0.21"
     id("com.diffplug.spotless") version "6.25.0"
     id("com.github.johnrengelman.shadow") version "8.1.1"
 }