Support for Python 3.10

[rjjanuary]

Usage of the "loop" variable within asyncio was deprecated in 3.8. Now in 3.10 it appears the use of the variable now errors.

Good news seems to be simply removing the use of loop allows the code to work "as is". I'm still trying to wrap my brain around the library, however at least wanted to drop a message that support for 3.10+ may be easy to implement.

[Z3R021]

@rjjanuary, I was able to get it to work locally with 3.10 by just dropping that param and you are correct that it is easy. Definitely be a breaking change with it then requiring 3.10. We just implemented the aiosfstream project and had to put it on 3.9.

[Andrei-Pozolotin]

1. works in this fork:
   https://github.com/random-python/x_aiocometd

2. use with pip via requirements.txt:

### aiocometd == 0.4.5 ### disable
aiocometd @ git+https://github.com/random-python/x_aiocometd@develop ### enalbe

[syphar]

@robertmrk what would be the way forward here?

I admit I don't know asyncio in that much detail, but I assume that the loop parameter is just not needed any more here? Or why else would they remove it?

Or would you accept a PR that just checks the python version and omits the loop from the initialization for >3.10?

[stefanmohl]

There hasn't been any activity from the maintainer for 4-5 years now. Perhaps @Andrei-Pozolotin could open his https://github.com/random-python/x_aiocometd repo for issue posting and we continue there?