The bottom of the README currently says

but the minimum is actually Python 3.9, since pyperf 2.8.1 (Nov 2024)

I'm happy to submit a PR, I propose

1. Delete the README line (so it can't fall out of sync again)
2. Optionally, add a shields.io badge, e.g. (based on https://shields.io/badges/python-version-from-pep-621-toml)

That particular badge would convery the information on GIthub, but sometimes it would contradict the information on PyPI - e..g if the latest release supports Python 3. but the unreleased main branch declares 3.<x+1>.