Fix E501: shorten long comment line in test_fixture.py

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

Author: archTortugax

dbdiff/tests/test_fixture.py

@@ -28,6 +28,6 @@ def test_diff_exact_match_returns_none(self):
         # Regression: the always-False `not diff` (imported function) bug
         # caused diff() to never return None, leaking temp files and breaking
         # assertNoDiff() with a TypeError on exact matches.
-        # Fixture contains: [{"model": "auth.group", "pk": 1, "fields": {"name": "initial_name"}}]
+        # Fixture: [{"model": "auth.group", "pk": 1, "fields": {"name": "initial_name"}}]
         Group.objects.create(id=1, name='initial_name')
         assert self.fixture.diff() is None