gitlab-branch-rename 0.1.0

To support Black Lives Matter and try to create safer spaces, I wanted to renameall of my own default branches in Gitlab. I wasn't able to find any tools to do that, so I wrote this one. If you're unsure why this is important or want to better understand my personal understandingof why I wanted to make these changes, see this Twitter thread: https://twitter.com/mislav/status/1270388510684598272