feat: update lints

Author: deandreamatias

example/lib/main.dart

@@ -5,7 +5,7 @@ import 'package:form_builder_file_picker/form_builder_file_picker.dart';
 void main() => runApp(const MyApp());
 
 class MyApp extends StatelessWidget {
-  const MyApp({Key? key}) : super(key: key);
+  const MyApp({super.key});
 
   @override
   Widget build(BuildContext context) {
@@ -18,7 +18,7 @@ class MyApp extends StatelessWidget {
 }
 
 class MyHomePage extends StatefulWidget {
-  const MyHomePage({Key? key}) : super(key: key);
+  const MyHomePage({super.key});
 
   @override
   MyHomePageState createState() => MyHomePageState();

pubspec.yaml

@@ -30,6 +30,6 @@ platforms:
   windows:
 
 dev_dependencies:
-  flutter_lints: ^2.0.3
+  flutter_lints: ^4.0.0
   flutter_test:
     sdk: flutter