feat: Move to Flutter 3.0.0 and Dart 2.17.0 (#1713)

This upgrades all packages to Flutter 3.0.0 and fixes all analyze issues that came from that.

packages/flame_rive/example/lib/main.dart

@@ -10,7 +10,7 @@ void main() {
 }
 
 class MyApp extends StatefulWidget {
-  const MyApp({Key? key}) : super(key: key);
+  const MyApp({super.key});
 
   @override
   State<MyApp> createState() => _MyAppState();