Twelve: Enable kotlin serialization plugin

Change-Id: If5b2828c627616c17c350d0a428fe658a69caac6
diff --git a/app/Android.bp b/app/Android.bp
index bfbcf90..3fcfa8a 100644
--- a/app/Android.bp
+++ b/app/Android.bp
@@ -37,6 +37,10 @@
         "-Aroom.schemaLocation=packages/apps/Twelve/app/schemas",
     ],
 
+    kotlin_plugins: [
+        "kotlin-serialize-compiler-plugin",
+    ],
+
     static_libs: [
         // DO NOT EDIT THIS SECTION MANUALLY
         "androidx.activity_activity",