Test against pypy-3.12

[jwodder]

No description provided.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 98.68%. Comparing base (46d4933) to head (2d59f98).

Additional details and impacted files

@@           Coverage Diff           @@
##           master      #57   +/-   ##
=======================================
  Coverage   98.68%   98.68%           
=======================================
  Files           3        3           
  Lines         458      458           
  Branches       89       89           
=======================================
  Hits          452      452           
  Misses          3        3           
  Partials        3        3           

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