chore(deps): update kotlin_version to v2.0.21

[renovate[bot]]

This PR contains the following updates:

Package	Change	Age	Adoption	Passing	Confidence
org.jetbrains.kotlin.plugin.compose	2.0.20 -> 2.0.21
org.jetbrains.kotlin.jvm	2.0.20 -> 2.0.21
org.jetbrains.kotlin:kotlin-serialization (source)	2.0.20 -> 2.0.21
org.jetbrains.kotlin:kotlin-gradle-plugin (source)	2.0.20 -> 2.0.21

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Release Notes

JetBrains/kotlin (org.jetbrains.kotlin:kotlin-serialization)

### [`v2.0.21`](https://redirect.github.com/JetBrains/kotlin/releases/tag/v2.0.21): Kotlin 2.0.21 ##### Changelog ##### Apple Ecosystem - [`KT-69093`](https://youtrack.jetbrains.com/issue/KT-69093) Xcode 16 support in Kotlin ##### Backend. Native. Debug - [`KT-71374`](https://youtrack.jetbrains.com/issue/KT-71374) lldb: step out breaks breaking in Xcode 16 ##### Compiler ##### Fixes - [`KT-69735`](https://youtrack.jetbrains.com/issue/KT-69735) K2: Static fields are missing from the declaration list of corresponding IrClass for java class - [`KT-71122`](https://youtrack.jetbrains.com/issue/KT-71122) Regression in Kotlin Compiler 2.0 causing NPE in the runtime - [`KT-70931`](https://youtrack.jetbrains.com/issue/KT-70931) K2 / Scripts: "cannot convert IrExpression to ConstantValue" when using function annotation - [`KT-70584`](https://youtrack.jetbrains.com/issue/KT-70584) K2: "IllegalStateException: flow for PostponedLambdaExitNode not initialized - traversing nodes in wrong order?" - [`KT-70808`](https://youtrack.jetbrains.com/issue/KT-70808) K2: "node has already been visited" with anonymous object in dead code - [`KT-69985`](https://youtrack.jetbrains.com/issue/KT-69985) K2: Classifier declarations from root package are resolved without imports in non-root packages - [`KT-70683`](https://youtrack.jetbrains.com/issue/KT-70683) K2: Internal compiler error in IrFakeOverrideSymbolBase.getOwner - [`KT-70901`](https://youtrack.jetbrains.com/issue/KT-70901) False positive Public-API inline function cannot access non-public-API property accessor - [`KT-70930`](https://youtrack.jetbrains.com/issue/KT-70930) K2: Java annotations not present on ENUM_ENTRY IR elements - [`KT-70194`](https://youtrack.jetbrains.com/issue/KT-70194) K2 IDE: exception on a very red file - [`KT-69399`](https://youtrack.jetbrains.com/issue/KT-69399) Native: IllegalStateException: "Failed to build cache" ##### Compose compiler ##### Fixes - [`b/329477544`](https://issuetracker.google.com/issues/329477544) Force open / overridden Composable functions to be non-restartable. - [`b/361652128`](https://issuetracker.google.com/issues/361652128) Disable live literal transform if the corresponding flag is disabled ##### IR. Actualizer - [`KT-70894`](https://youtrack.jetbrains.com/issue/KT-70894) IR crash. Unprocessed `IrFunctionFakeOverrideSymbol` when actualize to Java ##### IR. Tree - [`KT-71191`](https://youtrack.jetbrains.com/issue/KT-71191) SymbolTable: Check if the provided signature is public before adding a symbol to the SymbolTable ##### Native. Build Infrastructure - [`KT-71485`](https://youtrack.jetbrains.com/issue/KT-71485) K/N runtime parts don't build due to \_Float16 issues on x86\_64 macOS ##### Native. C Export - [`KT-69507`](https://youtrack.jetbrains.com/issue/KT-69507) LLVM 11 clang with Xcode 16 headers: standard c++ headers ##### Native. C and ObjC Import - [`KT-71029`](https://youtrack.jetbrains.com/issue/KT-71029) Investigate why stdarg.h declarations leak into testModuleA ##### Native. Platform Libraries - [`KT-70566`](https://youtrack.jetbrains.com/issue/KT-70566) LLVM 11 clang with Xcode 16 headers: 'sys/cdefs.h' file not found - [`KT-71624`](https://youtrack.jetbrains.com/issue/KT-71624) Eliminate remaining UIKit/AppKit removed signatures - [`KT-70031`](https://youtrack.jetbrains.com/issue/KT-70031) Rebuild platform libraries in 2.0.21 with Xcode 16 ##### Native. Testing - [`KT-70603`](https://youtrack.jetbrains.com/issue/KT-70603) C++ with -fmodules: cyclic dependency in module 'std': std -> \_wctype -> \__wctype -> std in dev llvm toolchains ##### Tools. CLI. Native - [`KT-71262`](https://youtrack.jetbrains.com/issue/KT-71262) KotlinNativeLink tasks fetching from network despite -Xoverride-konan-properties=dependenciesUrl= being set ##### Tools. Compiler Plugins - [`KT-71038`](https://youtrack.jetbrains.com/issue/KT-71038) PowerAssert: Constant on RHS of elvis operator leads to compiler crash ##### Tools. Daemon - [`KT-35381`](https://youtrack.jetbrains.com/issue/KT-35381) Get rid of the native-platform usage in kotlin compiler ##### Tools. Gradle. Multiplatform - [`KT-71444`](https://youtrack.jetbrains.com/issue/KT-71444) Certain POMs produced by Kotlin 2.0.20 cannot be consumed by KMP projects with Android targets - [`KT-70700`](https://youtrack.jetbrains.com/issue/KT-70700) Gradle 8.10: The value for task ':commonizeNativeDistribution' property 'kotlinNativeBundleBuildService' cannot be changed any further - [`KT-71396`](https://youtrack.jetbrains.com/issue/KT-71396) Gradle client side JVM explodes with OOM due to xcodebuild logs ##### Tools. Gradle. Native - [`KT-71419`](https://youtrack.jetbrains.com/issue/KT-71419) Light bundle KGP IT run against a stable K/N version ##### Tools. JPS - [`KT-71450`](https://youtrack.jetbrains.com/issue/KT-71450) Constant build failure: com.intellij.util.io.ClosedStorageException: storage is already closed

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