Update dependency org.jetbrains.kotlin:kotlin-gradle-plugin to v2.0.21 (

#324)

##### 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

Co-authored-by: renovate[bot] <29139614+renovate[bot]@users.noreply.github.com>

gradle/libs.versions.toml

@@ -1,5 +1,5 @@
 [versions]
-kotlin = "2.0.20"
+kotlin = "2.0.21"
 dokka = "1.9.20"
 openapi-generator = "7.8.0"
 jupyter-api = "0.12.0-310"