Bump org.jetbrains.kotlin.jvm in /integration-tests

Bumps [org.jetbrains.kotlin.jvm](https://github.com/JetBrains/kotlin) from 1.8.20 to 1.8.21.
- [Release notes](https://github.com/JetBrains/kotlin/releases)
- [Changelog](https://github.com/JetBrains/kotlin/blob/master/ChangeLog.md)
- [Commits](JetBrains/kotlin@v1.8.20...v1.8.21)

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

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

Author: dependabot[bot]

integration-tests/build.gradle.kts

@@ -4,7 +4,7 @@ import org.jetbrains.intellij.tasks.PatchPluginXmlTask
 fun properties(key: String) = project.findProperty(key).toString()
 
 plugins {
-    id("org.jetbrains.kotlin.jvm") version "1.8.20" apply false
+    id("org.jetbrains.kotlin.jvm") version "1.8.21" apply false
     id("org.jetbrains.kotlin.plugin.sam.with.receiver") version "1.8.21"
     id("org.jetbrains.intellij") version "0.0.0" apply false
     `kotlin-dsl`