Update kotlin monorepo to v2.1.21

[renovate]

This PR contains the following updates:

Package	Change	Age	Adoption	Passing	Confidence
org.jetbrains.kotlin:kotlin-test-junit (source)	2.1.20 -> 2.1.21
org.jetbrains.kotlin:kotlin-test (source)	2.1.20 -> 2.1.21
org.jetbrains.kotlin:kotlin-gradle-plugin (source)	2.1.20 -> 2.1.21

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Release Notes

JetBrains/kotlin (org.jetbrains.kotlin:kotlin-test-junit)

v2.1.21: Kotlin 2.1.21

Changelog

Backend. Native. Debug

• KT-75991 Xcode 16.3: Fix lldb stepping test over an inline function

Compiler

• KT-75992 Xcode 16.3: stacktraces on simulators are not symbolicated
• KT-76663 KJS: KotlinNothingValueException caused by expression return since 2.1.20
• KT-75756 Backend Internal error: Exception during IR lowering when trying to access variable from providedProperties in class within kotlin custom script
• KT-76209 CONFLICTING_UPPER_BOUNDS on Nothing bound
• KT-70352 K2: False-negative CONFLICTING_UPPER_BOUNDS on Nothing bound
• KT-74739 Native: "IllegalArgumentException: All constructors should've been lowered: FUNCTION_REFERENCE"
• KT-75483 Native: redundant unboxing generated with smart cast
• KT-71425 IR Inliner: investigate return type of an inlined block

Native

• KT-76252 Native: executable crash with generic value classes with 2.1.20

Native. C and ObjC Import

• KT-75781 Xcode 16.3: Fix cinterop tests failing with fatal error: could not build module '_stdint'

Native. Runtime. Memory

• KT-74280 Native: GC.collect crashes with -Xallocator=std

Tools. CLI

• KT-75588 [2.1.20-RC] "was compiled by a pre-release version of Kotlin and cannot be loaded by this version of the compiler" warnings despite using the same compiler version
• KT-74663 kotlinc-js CLI: not providing -ir-output-dir results in NullPointerException

Tools. Compiler Plugins

• KT-76162 "IllegalStateException: No mapping for symbol: VALUE_PARAMETER INSTANCE_RECEIVER" after updating to 2.1.20

Tools. Gradle

• KT-73682 Compatibility with Gradle 8.12 release
• KT-73142 Kotlin Gradle plugin: Remove usage of Gradle's internal ExecHandleBuilder
• KT-36004 Update 'org.gradle.usage' attribute rules to support the 'JAVA_API' and 'JAVA_RUNTIME' value
• KT-73968 KotlinDependencyManagement tries to mutate configuration after it was resolved
• KT-73684 Run integration tests against Gradle 8.12
• KT-72694 Accessing Task.project during execution is being deprecated in Gradle 8.12
• KT-73683 Compile against Gradle API 8.12

Tools. Gradle. JS

• KT-77119 KJS: Gradle: Setting custom environment variables in KotlinJsTest tasks no longer works
• KT-74735 KGP uses Gradle internal CompositeProjectComponentArtifactMetadata
• KT-71879 Notice of upcoming deprecation for Boolean 'is-' properties in Gradle Groovy scripts

Tools. Gradle. Multiplatform

• KT-75808 KGP: MPP with jvm target and Gradle java-test-fixtures is broken
• KT-75605 Dependency resolution fails in commonTest/nativeTest source sets for KMP module when depending on another project due to missing PSM
• KT-75512 Maven-publish: ArtifactId is not correct inpom file with customized withXml

Tools. Incremental Compile

• KT-62555 Wrong ABI fingerprint for inline function containing a lambda
• KT-75883 Follow-up: switch from INSTANCE heuristic to outerClass chain

Tools. Kapt

• KT-75936 K2 KAPT: unsupported FIR element kinds in constant evaluation
• KT-75942 K2 KAPT: underscore not allowed here

Tools. Scripts

• KT-76424 Dependencies in main.kts not working with 2.1.20
• KT-76296 Kotlin script compiler crashes when secondary constructor calls a function
• KT-75589 Scripts: "IndexOutOfBoundsException in jdk.internal.util.Preconditions.outOfBounds" when trying to extend a class which uses global variable

Tools. Wasm

• KT-76161 Wasm: "export startUnitTests was not found" after updating to Kotlin 2.1.20

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