Ignore QSaveFile::commit warning message in tests

The test (`test_failing_flush()`) is deliberately trying to write to a
close file. This is a new error in Qt 6.8 it seems.

Ignore just the specific file for this test in case it pops up somewhere
else later.

pytest.ini

@@ -77,6 +77,7 @@ qt_log_ignore =
     # model, for example, when no completion function is available for the
     # current text pattern.
     QItemSelectionModel: Selecting when no model has been set will result in a no-op.
+    ^QSaveFile::commit: File \(.*/test_failing_flush0/foo\) is not open$
 xfail_strict = true
 filterwarnings =
     error