tiniest of fixes

lib/components/connect_button.dart

@@ -84,7 +84,7 @@ class _ConnectButtonState extends State<ConnectButton>
         return;
       }
       final ok = await vpn.connect();
-      if (ok) timer.start('main_ad');
+      if (ok) timer.start();
     } finally {
       if (mounted) setState(() => _busy = false);
     }

lib/logic/session_timer.dart

@@ -88,7 +88,7 @@ class SessionTimer extends ChangeNotifier {
     }
   }
 
-  Future<void> start(String adType) async {
+  Future<void> start() async {
     _remainingSeconds    = 0;
     _usedBytes           = 0;
     _lastUsedBytes       = 0;