I found multiple issues / PR about action version updates. These are got closed because they are duplicates:

• Bump up setup-python #175
• Update main.yml #181
• Update main.yml #182
• Upgrade from github action v3 to v4 #186
• Update README.md #192
• Update main.yml #193

This is not the newest one; I think this was the one being referred to as the original for some:

• Update action checkout, cache, python #188

but, it got closed too. In the end, that update is still not merged.

@asottile I can create a new PR or we can open #188 back.