Drop Python 3.9 and use Python 3.11 official release

[micahellison]

We'll plan on merging this in late October or early November, after the official 3.11 release comes out and the GitHub actions are working appropriately, but I wanted to open this ahead of time so contributors are aware.

This conforms to the schedule in #1406, as it's about 6 months since the last Python 3.9 release.

Checklist

• I have read the contributing doc.
• I have included a link to the relevant issue number.
• I have checked to ensure there aren't other open pull requests
  for the same issue.
• I have written new tests for these changes, as needed.

[micahellison]

Looks like I modified the version a bit too soon. After this updates to include 3.11.0, I'll re-run the checks and they should hopefully go back to passing.

[wren]

🐍

[wren]

🐍 🐍