Use non-deprecated Kotlin DSL for Kotlin compile options

[CXwudi]

In recent version of Kotlin Gradle Plugin, tasks.withType<KotlinCompile>.kotlinOptions is marked as deprecated

A better DSL is:

import org.jetbrains.kotlin.gradle.dsl.JvmTarget

kotlin {
  compilerOptions {
    freeCompilerArgs = freeCompilerArgs.get() + listOf("-Xjsr305=strict")
    jvmTarget = JvmTarget.JVM_21
  }
}

[mhalbritter]

One problem I stumbled upon is that there's no JvmTarget.JVM_22.