GitHub Actions: Add PyPy 3.10 to testing

[cclauss]

A subset of

• 2634

Thanks for contributing, make sure you address all the checklists (for details on how see development documentation)

• [ ] ran the linter to address style issues (tox -e fix)
• [x] wrote descriptive pull request title
• [ ] ensured there are test(s) validating the fix
• [ ] added news fragment in docs/changelog folder
• [ ] updated/extended the documentation

[cclauss]

Nice!!