[skip ci] Opt in ExperimentalSerializationApi for multisrc theme (#13523)

multisrc/build.gradle.kts

@@ -14,6 +14,10 @@ android {
         minSdk = 29
         targetSdk = AndroidConfig.targetSdk
     }
+
+    kotlinOptions {
+        freeCompilerArgs += "-Xopt-in=kotlinx.serialization.ExperimentalSerializationApi"
+    }
 }
 
 repositories {

multisrc/src/main/java/eu/kanade/tachiyomi/multisrc/mccms/MCCMS.kt

@@ -124,7 +124,6 @@ open class MCCMS(
     override fun imageUrlParse(response: Response) = throw UnsupportedOperationException("Not used.")
 
     private inline fun <reified T> Response.parseAs(): T = use {
-        @Suppress("OPT_IN_USAGE")
         json.decodeFromStream<ResultDto<T>>(it.body!!.byteStream()).data
     }