- >= 3.10 add a warning that `get_event_loop` will not automatically create a loop
- Move to explicit API

Test:
- `python3.11 -m venv --upgrade-deps /tmp/tb`
  - `/tmp/tb/bin/pip install -e .`
  - Install deps and no blackd as aiohttp + yarl can't build still with 3.11
  - aio-libs/aiohttp#6600
- `export PYTHONWARNINGS=error`
```
cooper@l33t:~/repos/black$ /tmp/tb/bin/black .
All done! ✨ 🍰 ✨
44 files left unchanged.
```

Fixes #3110

Fix my silly typo.

Co-authored-by: Thomas Grainger <tagrain@gmail.com>