[yt-dev] Change default branch name

Hi folks, In January, Github is making it easier to change the default branch name with a toggle on the website: https://github.com/github/renaming I know lots of other projects have done this (including maestro) and we could do it ourselves, but I'd like to propose that we do this as soon as GH has the tooling in place to handle it for us. If anyone objects we can dig into this during a team meeting or something, but personally this kind of seems uncontroversial and should be easy to implement. -Matt