Fix name of pytest fixture to avoid collision

Author: adamchainz

tests/testapp/test_cache.py

@@ -1300,7 +1300,7 @@ def test_cull_mysql_caches_bad_cache_name(self):
 @override_cache_settings()
 class MySQLCacheMigrationTests(MySQLCacheTableMixin, TransactionTestCase):
     @pytest.fixture(autouse=True)
-    def flake8_path(self, flake8_path):
+    def set_flake8_path(self, flake8_path):
         self.flake8_path = flake8_path
 
     def test_mysql_cache_migration(self):