Move DM timestamps to the bottom of the message from the right

lib/screens/message_thread_screen.dart

@@ -91,7 +91,7 @@ class _MessageThreadScreenState extends State<MessageThreadScreen> {
                               ? null
                               : const TextStyle(fontWeight: FontWeight.bold),
                         ),
-                        trailing: Text(DateTime.fromMillisecondsSinceEpoch(
+                        subtitle: Text(DateTime.fromMillisecondsSinceEpoch(
                                 m.createdAt * 1000)
                             .toString()),
                       );