Support Python 3.11

[hugovk]

Python 3.11 beta is out on Friday with full release in October:

• 3.11.0 beta 1: Friday, 2022-05-06
• 3.11.0 final: Monday, 2022-10-03

https://peps.python.org/pep-0664/

Changes proposed in this pull request:

• Test 3.11-dev on GitHub Actions
• Add py311 to tox.ini
• Add Trove classifier
• Update some config

[codecov-commenter]

Codecov Report

Merging #13 (4faef03) into main (52b0aab) will decrease coverage by 1.25%.
The diff coverage is n/a.

@@            Coverage Diff             @@
##             main      #13      +/-   ##
==========================================
- Coverage   99.68%   98.42%   -1.26%     
==========================================
  Files           9        9              
  Lines         635      635              
==========================================
- Hits          633      625       -8     
- Misses          2       10       +8     

Flag	Coverage Δ
GHA_Ubuntu	?
GHA_Windows	?
GHA_macOS	?
macos-latest	97.48% <ø> (?)
ubuntu-latest	98.42% <ø> (?)

Flags with carried forward coverage won't be shown. Click here to find out more.

Impacted Files	Coverage Δ
tests/test_i18n.py	88.88% <0.00%> (-11.12%)	⬇️

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