Change default branch to `main`.

[francium]

There's some ongoing work, don't want to change until that's completed to avoid disrupting things.

[chuckwondo]

Hi @francium! Thanks for this library. I plan to open some PRs in the near future. Any estimate on making this default branch change?

[francium]

Just go ahead with your PRs, this change isn't urgent, it can be done after.

[chuckwondo]

Yep, was just curious.