Revert "Add latest Python versions (#109)"

[mblaymanbot]

Summary

• revert the surviving python-tap/tappy#109 changes that still exist on current main
• remove the Python 3.8 support lines in the README and docs that still blame back to #109
• leave the modern build/config stack alone instead of trying to resurrect deleted .travis.yml or setup.py

Notes

• this was a conflict-heavy revert because #109 was merged into master in 2020 and the repo has changed substantially since then
• the resulting revert commit is intentionally small and only touches the three lines that still descend from #109

Testing

• not run locally (pytest is not installed in this environment)

[mblaymanbot]

Closing this draft because it was opened against the wrong repository. The intended revert target is python-tap/pytest-tap#109.