Support for Python 3.11

[Rongronggg9]

https://docs.python.org/3.11/whatsnew/3.11.html

I've tested the existing GHA workflow. It is broken. I may help fix it.

Another problem is dropping Python 3.6 support or not, as PyO3 has dropped it in v0.16.0. If it can be dropped, we can bump PyO3 to its latest version so that adding Python 3.11 support won't be difficult. I may help with it too.

[Lonami]

cryptg is not required to run Telethon, and given that 3.6 has reached EOL:

As of 2021-12-23, 3.6 has reached the end-of-life phase of its release cycle

I'm okay with dropping support for it. (Users can still use an older version as there are virtually no functionality changes.)

[Rongronggg9]

Sure, I am working on it :)