Support for python 3.11

[headtr1ck]

Is your feature request related to a problem?

Now that python 3.11 has been released, we should start to support it officially.

Describe the solution you'd like

I guess the first step would be to replace python 3.10 as a maximum version in the tests and see what crashes (and get lucky).

Describe alternatives you've considered

No response

Additional context

No response

[dcherian]

Usually the full test env is limited by numba. I think for 3.10 we created a new test workflow without numba. So that could be a good way to go.

[sxwebster]

@dcherian Numba is looking at having a Python 3.11 RC ready by end of year, hopefully. It would be lovely to see Numba + Xarray catch up as 3.11 (and 3.12) look to have some big speed improvements.