Fix lint issues

Author: ashtanko

lib/models/rocket/rocket_resource.dart

@@ -1,7 +1,5 @@
 import 'package:equatable/equatable.dart';
 import 'package:flutter/foundation.dart';
-import 'package:flutter_bloc_app_template/models/rocket/rocket_first_stage_resource.dart';
-import 'package:flutter_bloc_app_template/models/rocket/rocket_second_stage_resource.dart';
 
 import 'rocket.dart';