fix: remove double-call on AsyncSession in SerieScanner

get_async_session_factory() returns session directly, not factory.
Calling result again with () caused 'AsyncSession' object is not callable.

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

tests/unit/test_serie_scanner_db_writes.py

@@ -209,7 +209,7 @@ class TestPersistSerieToDbErrorHandling:
 
         with patch(
             "src.server.database.connection.get_async_session_factory",
-            return_value=mock_factory
+            return_value=mock_session
         ):
             with patch(
                 "src.server.database.service.AnimeSeriesService.get_by_key",