Support GitHub default branches #14
Description
While pulldozer expects the default branch of the repos it clones to be master, GitHub now uses main as the default branch. As this value can be different per-repository, the proper fix would probably involve obtaining the default_branch value from the GitHub API.
Happy to help with putting a PR around that together -- I just wanted to first discuss what would be the best way of doing that withing the current setup.
Thanks!
cc @mayhewsw