Update protobuf pubspec.yaml (#616)
Update protobuf pubspec.yaml (#616)


dart-lang/dart-protobuf,dart-lang/dart-protobuf,dart-lang/protobuf,dart-lang/protobuf,google/protobuf.dart,dart-lang/dart-protobuf,google/protobuf.dart,google/protobuf.dart,dart-lang/protobuf