fix: skip commitizen's stale py_3_13 invalid-command test

commitizen 4.13.9 ships per-Python-minor golden files for its CLI
regression tests. The py_3_13 golden was captured against an early 3.13
whose argparse did not quote invalid choices. CPython later backported
quoting into the 3.13.x line, and nixos-26.05 now ships 3.13.14, so the
golden no longer matches argparse's output:

  -cz: error: ... invalid choice: 'x' (choose from init, commit, ...)
  +cz: error: ... invalid choice: 'x' (choose from 'init', 'commit', ...)

This fails commitizen's checkPhase and breaks the home-manager closure.
The package itself is unaffected. Deselect just that test via an overlay
until nixpkgs updates the fixture (or the 3.13.x revert lands upstream).

flake.nix

@@ -95,6 +95,16 @@
               claude-code
               ;
           })
+          # commitizen 4.13.9's regression test for the invalid-command error
+          # message asserts argparse's older, unquoted "invalid choice" wording;
+          # the argparse in Python 3.13 quotes each choice, so the fixture no
+          # longer matches and the checkPhase fails. The package itself is fine
+          # -- deselect just that test. Drop once nixpkgs updates the fixture.
+          (_final: prev: {
+            commitizen = prev.commitizen.overridePythonAttrs (old: {
+              disabledTests = (old.disabledTests or [ ]) ++ [ "test_invalid_command" ];
+            });
+          })
         ];
 
         # Unfree packages permitted to be built (replaces blanket allowUnfree).