Update Python versions in the CI workflow.

[ezio-melotti]

Same as:

• Update Python versions in the CI workflow. blurb_it#316

[codecov]

Codecov Report

Merging #520 (32407d6) into main (ea0353f) will not change coverage.
The diff coverage is n/a.

@@            Coverage Diff            @@
##              main      #520   +/-   ##
=========================================
  Coverage   100.00%   100.00%           
=========================================
  Files           18        18           
  Lines         2034      2034           
  Branches       231       231           
=========================================
  Hits          2034      2034           

Flag	Coverage Δ
Python_3.10.8	100.00% <ø> (ø)
Python_3.11.0	100.00% <ø> (ø)
Python_3.12.0-alpha.2	100.00% <ø> (?)
Python_3.8.14	100.00% <ø> (ø)
Python_3.9.15	100.00% <ø> (ø)

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[hugovk]

Let's also add 312 to tox.ini

envlist = py{311, 310, 39, 38}

[hugovk]

Thanks!