gitlab-branch-rename 0.6.0

To support Black Lives Matter and create safer spaces, I wanted to rename all of the default branches in my Gitlab account. 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 why I wanted to make these changes, see this great {Twitter thread}[https://twitter.com/mislav/status/1270388510684598272].