Update Kotlin to 2.3.20 (#1185)

[SKIKO-1067](https://youtrack.jetbrains.com/issue/SKIKO-1067) Build
Skiko with Kotlin 2.3.0

dependencies.toml

 [versions]
-kotlin = "2.2.20"
+kotlin = "2.3.20"
 kotlinxBrowser = "0.5.0"
 
 coroutines = "1.8.0"

samples/SkiaAndroidSample/build.gradle.kts

@@ -23,7 +23,7 @@ repositories {
 
 plugins {
     id("com.android.application") version "8.9.0"
-    kotlin("android") version "2.2.20"
+    kotlin("android") version "2.3.20"
 }
 
 val skikoNativeX64 by configurations.creating

samples/SkiaAwtSample/build.gradle.kts

 import org.jetbrains.kotlin.gradle.tasks.KotlinCompile
 
 plugins {
-    kotlin("jvm") version "2.2.20"
+    kotlin("jvm") version "2.3.20"
     application
 }
 

samples/SkiaMultiplatformSample/gradle.properties

 kotlin.code.style=official
 org.gradle.jvmargs=-Xmx3G -XX:MaxMetaspaceSize=512m
-kotlin.version=2.2.20
+kotlin.version=2.3.20
 skiko.version=0.144.0
 #skiko.composite.build=1

samples/SkiaWebSample/gradle.properties

 kotlin.code.style=official
-kotlin.version=2.2.20
+kotlin.version=2.3.20
 skiko.version=0.144.0
 #skiko.composite.build=1

skiko/buildSrc/gradle.properties

-kotlin.version=2.2.20
+kotlin.version=2.3.20

skiko/import-generator/src/jvmMain/kotlin/org/jetbrains/skiko/ImportGeneratorRegistrar.kt

@@ -8,6 +8,7 @@ import org.jetbrains.kotlin.config.CompilerConfiguration
 @OptIn(ExperimentalCompilerApi::class)
 class ImportGeneratorRegistrar : CompilerPluginRegistrar() {
     override val supportsK2: Boolean = true
+    override val pluginId: String = "skiko-import-generator"
 
     override fun ExtensionStorage.registerExtensions(
         configuration: CompilerConfiguration,