give Sergio developer status to the Arduino repo

I realize that the Guess role does not allow you to even see the code. The Reporter role allows you to see the code, but you can't do pull requests.

In order for us to test Gitlab, we need to be able to collaborate in a real repo. I will be the Maintainer/Developer and you the Developer for my Arduino repo, and you can make me Reporter or Developer of one of your test repos is you like, so you can also test what is to be the Maintainer.