refactor: Update flutter lints

lib/widgets/app_lock.dart

@@ -41,7 +41,7 @@ class AppLock extends State<AppLockWidget> with WidgetsBindingObserver {
     WidgetsBinding.instance.addPostFrameCallback(_checkLoggedIn);
   }
 
-  void _checkLoggedIn(_) async {
+  void _checkLoggedIn(dynamic _) async {
     if (widget.clients.any((client) => client.isLogged())) return;
 
     await changePincode(null);

lib/widgets/theme_builder.dart

@@ -43,7 +43,7 @@ class ThemeController extends State<ThemeBuilder> {
         listen: false,
       );
 
-  void _loadData(_) async {
+  void _loadData(dynamic _) async {
     final preferences =
         _sharedPreferences ??= await SharedPreferences.getInstance();