update passing jvmArgs in samples to the latest Gradle (#1068)

fixes SKIKO-1035

samples/SkiaAwtSample/build.gradle.kts

@@ -56,8 +56,8 @@ val casualRun = tasks.named<JavaExec>("run") {
     systemProperty("skiko.hardwareInfo.enabled", "true")
     systemProperty("skiko.win.exception.logger.enabled", "true")
     systemProperty("skiko.win.exception.handler.enabled", "true")
-    jvmArgs?.add("-ea")
-    // jvmArgs?.add("-Xcheck:jni")
+    jvmArgs("-ea")
+    // jvmArgs("-Xcheck:jni")
     // Use systemProperty("skiko.library.path", "/tmp") to test loader.
     System.getProperties().entries
         .associate {

samples/SkiaMultiplatformSample/build.gradle.kts

@@ -244,7 +244,7 @@ project.tasks.register<JavaExec>("runAwt") {
     systemProperty("skiko.hardwareInfo.enabled", "true")
     systemProperty("skiko.win.exception.logger.enabled", "true")
     systemProperty("skiko.win.exception.handler.enabled", "true")
-    jvmArgs?.add("-ea")
+    jvmArgs("-ea")
     System.getProperties().entries
         .associate {
             (it.key as String) to (it.value as String)