Make black[d] install + test run with 3.12 (#4035)

* Make black[d] install + test run with 3.12

- With aiohttp >= 3.9.0 we can now install all dependencies with 3.12
- Add actions to run 3.12
- Lint still needs to be 3.11

Test:
- `python3.12 -m venv /tmp/tb --upgrade-deps`
- `/tmp/tb/bin/pip install tox`
- `/tmp/tb/bin/pip install .[d]`
- `/tmp/tb/bin/tox -e py312`
```
  py312: OK (37.61=setup[3.98]+cmd[3.83,0.36,19.54,6.46,3.00,0.44] seconds)
  congratulations :) (37.63 seconds)
```

* Move to pypy-3.9

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Co-authored-by: Jelle Zijlstra <jelle.zijlstra@gmail.com>