Cleanup stale release branches?

[brianschubert]

Finding the active release branch can be a pain due the abundance of stale branches which, for whatever reason, tend to be sorted first in GitHub's UI:

Are these branches still beneficial to keep around?

For comparison, CPython is in the habit of deleting maintenance once the associated version falls out of support. This makes finding relevant branches in the UI comparatively easier: https://github.com/python/cpython/branches