CI/CD Upgrade to Python 3.10

[cclauss]

Upgrade to actions/setup-python@v2 and Python 3.10

https://pythoninsider.blogspot.com/2021/10/python-3100-is-available.html

"3.10" must be quoted in YAML. https://dev.to/hugovk/the-python-3-1-problem-85g

[codecov[bot]]

Codecov Report

Merging #177 (5bfede0) into master (ec7d172) will decrease coverage by 0.96%. The diff coverage is n/a.

@@            Coverage Diff             @@
##           master     #177      +/-   ##
==========================================
- Coverage   95.02%   94.05%   -0.97%     
==========================================
  Files          13       13              
  Lines        1868     1868              
  Branches      214      214              
==========================================
- Hits         1775     1757      -18     
- Misses         80       95      +15     
- Partials       13       16       +3     

Impacted Files	Coverage Δ
src/hyperlink/test/test_hypothesis.py	82.17% <0.00%> (-1.99%)	:arrow_down:
src/hyperlink/hypothesis.py	93.96% <0.00%> (-1.73%)	:arrow_down:
src/hyperlink/_url.py	95.65% <0.00%> (-1.50%)	:arrow_down:
src/hyperlink/test/test_url.py	99.30% <0.00%> (-0.52%)	:arrow_down:

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