In case you missed this in the long release announcement e-mail, `master` was renamed to `main` and unblocked so you can now continue contributing without disruption. Well, almost. You need to:
1. go to your fork on GitHub and rename its default branch; and
2. update your local clones.
For both steps GitHub should give you nice by-the-hand instructions when you go to your fork's main page. The first one you do right away, and the second will be asynchronous, which took a minute or so on my own fork.
In case it doesn't for some reason, the full guide covering both steps is here:
Don't be shy to ask if you're unsure how to proceed.
Cheers,
Łukasz