Update kotlin monorepo to v2.4.21

[renovate]

This PR contains the following updates:

Package	Change	Age	Confidence
org.jetbrains.kotlin.plugin.serialization (source)	2.4.20 → 2.4.21
org.jetbrains.kotlin:kotlin-test-junit (source)	2.4.20 → 2.4.21

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Release Notes

JetBrains/kotlin (org.jetbrains.kotlin.plugin.serialization)

v2.4.21

Backend. Wasm

• KT-89267 K/Wasm: calling a (T) -> R lambda with an argument that isn't a T traps instead of throwing ClassCastException

JVM. Reflection

• KT-89280 NoSuchElementException in argumentsMakeSenseOnlyForMutableContainer for Java non-static inner class of generic outer class
• KT-80710 Reflection: change KCallable representation to avoid dependency on K1

JavaScript

• KT-89449 Kotlin/JS: Member names no longer minified in production
• KT-89363 KJS. Regular class with companion can't extend external class

Tools. Compiler plugins. Serialization

• KT-89275 Kotlin/Wasm: Invalid Wasm is emitted for a @Serializable generic class with a class upper bound

Tools. Gradle. Native

• KT-89285 SwiftPM import results in flooded log
• KT-86251 K/N: Flaky linkDebugTestLinuxX64 failure with "truncated or malformed archive" on libstdlib-cache.a

Tools. Scripts

• KT-89247 Kotlin Script: NoClassDefFoundError on 2nd execution with transitive dependency from imported script
• KT-89220 JSR-223: generic Java bindings break all subsequent eval() calls
• KT-88458 Audit closeable resource usage
• KT-88453 VirtualFileScriptSource.text leaks an unclosed file stream — script source file handle held until GC, blocks file deletion on Windows

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