Along with the release of Python 3.9.0b1, a 3.9 maintenance branch was created and the master branch now holds work that will become Python 3.10a1 at some point. This change was made here: https://github.com/python/cpython/pull/20198
Note that this means you have to have your bugfix pull requests backported to 3.9 using the newly created GitHub label. If you don't do this, they will only be available in Python 3.10.
Note I wrote bugfix pull requests. We entered the beta phase and new features will have to wait until next year's release.
Creating a new maintenance branch is the most manual piece of the release process we have. If you notice any place where Python 3.10 is missing in a list, or that suggests that master is still Python 3.9, let me know and we'll handle it. Thank you to Victor Stinner who proactively found a bunch of those things very quickly. (Julien is taking care of the JS version pickers in the docs.)