Bump org.jetbrains.kotlin.jvm from 2.1.20 to 2.1.21 (#10)

Bumps [org.jetbrains.kotlin.jvm](https://github.com/JetBrains/kotlin) from 2.1.20 to 2.1.21.
- [Release notes](https://github.com/JetBrains/kotlin/releases)
- [Changelog](https://github.com/JetBrains/kotlin/blob/master/ChangeLog.md)
- [Commits](JetBrains/kotlin@v2.1.20...v2.1.21)

---
updated-dependencies:
- dependency-name: org.jetbrains.kotlin.jvm
  dependency-version: 2.1.21
  dependency-type: direct:production
  update-type: version-update:semver-patch
...

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

Author: dependabot[bot]

build.gradle

@@ -1,5 +1,5 @@
 plugins {
-    id 'org.jetbrains.kotlin.jvm' version '2.1.20'
+    id 'org.jetbrains.kotlin.jvm' version '2.1.21'
     id 'net.neoforged.moddev' version '2.0.88'
     id 'maven-publish'
     id 'java-library'