Support for Python 3.10

[tirkarthi]

This was reported in https://bugzilla.redhat.com/show_bug.cgi?id=1897245 . It seems 3.10 is missing from long_versions variable as I can see from previous PR that added 3.9 : eec6d91

[jackmaney]

Python 3.10 is still in alpha (the most recent release, as of this writing, being 3.10.0 alpha 5). While 3.10 is still in this state, changes to built-in modules are still possible. Once 3.10.0 final is out (which has a current ETA of 2021-10-04), please feel free to make an issue and/or pull request.