refactor(flutter_wizard): upgrade to null safety

Author: felangel

examples/flutter_wizard/ios/Runner.xcodeproj/project.xcworkspace/contents.xcworkspacedata

@@ -2,7 +2,6 @@ import 'dart:async';
 
 import 'package:bloc/bloc.dart';
 import 'package:equatable/equatable.dart';
-import 'package:meta/meta.dart';
 
 part 'profile_wizard_event.dart';
 part 'profile_wizard_state.dart';

examples/flutter_wizard/lib/bloc/profile_wizard_bloc.dart

@@ -1,7 +1,7 @@
 part of 'profile_wizard_bloc.dart';
 
 class Profile extends Equatable {
-  const Profile({@required this.name, @required this.age});
+  const Profile({required this.name, required this.age});
 
   final String? name;
   final int? age;

examples/flutter_wizard/lib/bloc/profile_wizard_state.dart

@@ -1,13 +1,9 @@
-import 'package:equatable/equatable.dart';
 import 'package:flutter/foundation.dart';
 import 'package:flutter/material.dart';
 import 'package:flutter_bloc/flutter_bloc.dart';
 import 'package:flutter_wizard/bloc/profile_wizard_bloc.dart';
 
-void main() {
-  EquatableConfig.stringify = kDebugMode;
-  runApp(MyApp());
-}
+void main() => runApp(MyApp());
 
 class MyApp extends StatelessWidget {
   @override

examples/flutter_wizard/lib/main.dart

@@ -14,7 +14,6 @@ dependencies:
   equatable: ^2.0.0
   flutter_bloc:
     path: ../../packages/flutter_bloc
-  meta: ^1.3.0
 
 dependency_overrides:
   bloc: