chore: update proguard.txt to reflect LiveObjects plugin renaming

Author: ttypic

android/proguard.txt

@@ -1,6 +1,6 @@
 -keep public class io.ably.lib.transport.WebSocketTransport$Factory {*;}
 -keep class io.ably.lib.types.** {*;}
--keep class io.ably.lib.objects.*ObjectsPlugin {*;}
+-keep class io.ably.lib.objects.*LiveObjectsPlugin {*;}
 -keep class io.ably.lib.objects.serialization.*Serializer {*;}
 -keep class io.ably.lib.objects.ObjectsJsonSerializer {*;}