use asyncio.Runner(loop_factory=...) instead of the policy system on 3.11

[graingert]

As part of the GELectomy (removing the per thread global eventloop from asyncio.get_event_loop() ) asyncio.runners now provides a policy free way to select the eventloop implementation. uvicorn should use this on 3.11 and consider backporting the implementation for other python versions

[Kludex]

Sure. Let's wait for the 3.11 support on underneath packages and go for it. 🙏

[Kludex]

Back here 👋

So...

It might be better to copy the implementation from python 3.10 asyncio.runners and ignore the broken implementation in 3.11

But shouldn't we wait for things to be fixed in CPython? 🤔