add 3.11 support

[cwmeijer]

This PR Fixes #623.

Why all the red crosses then?

• Does not fix fix failing conversion notebooks #626 about the failing notebook tests.
• Also, linting is failing, but has been fixed in main already. Has nothing to do with this PR.

[geek-yang]

Thanks for adding this @cwmeijer. Also a few places need to be updated:

• setup.cfg

  dianna/setup.cfg

  Lines 15 to 17 in 64d2c91

  	Programming Language :: Python :: 3.8
  	Programming Language :: Python :: 3.9
  	Programming Language :: Python :: 3.10

• CD/CI

  dianna/.github/workflows/build.yml

  Line 27 in 64d2c91

  python-version: '3.10'

  
  

  dianna/.github/workflows/build.yml

  Line 43 in 64d2c91

  python-version: ['3.8', '3.9', '3.10']

I will approve it. But please update the codes above as well. Thanks.

[cwmeijer]

@geek-yang , I updated as you suggested and also optimized our build config matrix. Do you agree with those changes as well?
Also see NLeSC/python-template#345.
Basically I only run the oldest and newest supported python versions. It's very unlikely that a single intermediate version would be broken.