[REQ] [Kotlin] Parcelize is now stable

[4brunu]

Is your feature request related to a problem? Please describe.

The feature Parcelize show's a warning in the console saying that is an experimentar feature, but since Kotlin 1.3.41 is now stable.

https://github.com/JetBrains/kotlin/blob/1.3.40/ChangeLog.md#tools-android-extensions

openapi-generator/modules/openapi-generator/src/main/java/org/openapitools/codegen/languages/AbstractKotlinCodegen.java

Lines 416 to 422 in 600a81f

	LOGGER.info(CodegenConstants.PARCELIZE_MODELS + " depends on the android framework and " +
	"experimental parcelize feature. Make sure your build applies the android plugin:\n" +
	"apply plugin: 'com.android.library' OR apply plugin: 'com.android.application'.\n" +
	"and enables the experimental features:\n" +
	"androidExtensions {\n" +
	" experimental = true\n" +
	"}"

Describe the solution you'd like

We can now remove the warning.