Add Python 3.13 to the testing matrix

[ezio-melotti]

Python 3.13 support was added to the setup-python action recently:

• https://github.com/actions/setup-python/issues/742

This PR adds it to the testing matrix.

[codecov[bot]]

Codecov Report

All modified and coverable lines are covered by tests :white_check_mark:

Project coverage is 100.00%. Comparing base (504dc34) to head (b3b5caf).

@@            Coverage Diff            @@
##              main      #597   +/-   ##
=========================================
  Coverage   100.00%   100.00%           
=========================================
  Files           18        18           
  Lines         2149      2149           
  Branches       245       245           
=========================================
  Hits          2149      2149           

Flag	Coverage Δ
Python_3.10.14	100.00% <ø> (ø)
Python_3.11.9	100.00% <ø> (ø)
Python_3.12.3	?
Python_3.12.4	100.00% <ø> (?)
Python_3.13.0-beta.2	100.00% <ø> (?)
Python_3.8.18	100.00% <ø> (ø)
Python_3.9.19	100.00% <ø> (ø)

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[hugovk]

Marking as draft.

3.12.0 was only released a couple of weeks ago, and we were only then able to add 3.12 due to missing dependency wheels, so this PR may be sitting around for a year or so...

[ezio-melotti]

The failure seems to be caused by multidict:

  ERROR: Failed building wheel for multidict
ERROR: Could not build wheels for multidict, which is required to install pyproject.toml-based projects

There are already a couple of related issues upstream:

• https://github.com/aio-libs/multidict/issues/862
• https://github.com/aio-libs/multidict/issues/887

[ezio-melotti]

I pinned cffi==v1.17.0rc1 (with a comment to remove it once the final version is out) and that solved the failures on 3.13. Now all the checks pass.