Support coroutines, migrate to Kotlin 1.21

samples/SkijaInjectSample/build.gradle

 plugins {
-    id 'org.jetbrains.kotlin.jvm' version '1.3.72'
+    id 'org.jetbrains.kotlin.jvm' version '1.4.21'
     id 'application'
 }
 
@@ -44,6 +44,7 @@ if (project.hasProperty('skiko.version')) {
 dependencies {
     implementation platform('org.jetbrains.kotlin:kotlin-bom')
     implementation 'org.jetbrains.kotlin:kotlin-stdlib-jdk8'
+    implementation 'org.jetbrains.kotlinx:kotlinx-coroutines-swing:1.4.1'
     implementation "org.jetbrains.skiko:skiko-jvm-runtime-$target:$version"
     testImplementation 'org.jetbrains.kotlin:kotlin-test'
     testImplementation 'org.jetbrains.kotlin:kotlin-test-junit'

skiko/build.gradle.kts

 import de.undercouch.gradle.tasks.download.Download
-import kotlin.text.capitalize
 import org.gradle.crypto.checksum.Checksum
 
 plugins {
-    kotlin("multiplatform") version "1.3.72"
+    kotlin("multiplatform") version "1.4.21"
     `cpp-library`
     `maven-publish`
     id("org.gradle.crypto.checksum") version "1.1.0"
@@ -169,6 +168,7 @@ kotlin {
             kotlin.srcDirs(skijaSrcDir)
             dependencies {
                 implementation(kotlin("stdlib-jdk8"))
+                implementation("org.jetbrains.kotlinx:kotlinx-coroutines-swing:1.4.1")
                 compileOnly(lombok)
                 compileOnly(jetbrainsAnnotations)
             }