fix(voltron): add license for flutter_render_test.dart

framework/voltron/test/flutter_render_test.dart

@@ -1,3 +1,23 @@
+//
+// Tencent is pleased to support the open source community by making
+// Hippy available.
+//
+// Copyright (C) 2022 THL A29 Limited, a Tencent company.
+// All rights reserved.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+//
+
 import 'package:flutter_test/flutter_test.dart';
 import 'package:voltron/inspector/dev_remote_server_data.dart';