Add Python 3.13 to test matrix

[ml-evs]

Closes #2161

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 90.80%. Comparing base (7198561) to head (6b0ef6b).
Report is 1 commits behind head on main.

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #2163   +/-   ##
=======================================
  Coverage   90.80%   90.80%           
=======================================
  Files          75       75           
  Lines        4819     4819           
=======================================
  Hits         4376     4376           
  Misses        443      443           

Flag	Coverage Δ
project	90.80% <ø> (ø)
validator	90.80% <ø> (ø)

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[ml-evs]

Looks like we're only held up by psycopg2 wheels (for AiiDA) needing to be rebuilt following the main release of 3.13 psycopg/psycopg2#1692. I don't think we're in a huge rush to support 3.13, and at some point the AiiDA tests/adapter might even be moved out to somewhere more maintainable.