Do not specify runtime retention explicitly, because of

https://youtrack.jetbrains.com/issue/KT-41082

Author: sandwwraith

runtime/commonMain/src/kotlinx/serialization/Annotations.kt

@@ -69,7 +69,7 @@ import kotlin.reflect.*
  * @see Serializer
  */
 @Target(AnnotationTarget.PROPERTY, AnnotationTarget.CLASS, AnnotationTarget.TYPE)
-@Retention(AnnotationRetention.RUNTIME)
+//@Retention(AnnotationRetention.RUNTIME) // Runtime is the default retention, also see KT-41082
 public annotation class Serializable(
     val with: KClass<out KSerializer<*>> = KSerializer::class // Default value indicates that auto-generated serializer is used
 )
@@ -209,7 +209,7 @@ public annotation class UseSerializers(vararg val serializerClasses: KClass<out
  * with special compiler plugin support which would be added later.
  */
 @Target(AnnotationTarget.PROPERTY, AnnotationTarget.TYPE, AnnotationTarget.CLASS)
-@Retention(AnnotationRetention.RUNTIME)
+//@Retention(AnnotationRetention.RUNTIME) // Runtime is the default retention, also see KT-41082
 public annotation class Polymorphic
 
 /**