Clean audit security scan and test resources

tests/test_audit_delivery.py

@@ -32,6 +32,7 @@ class AuditCommandBusTests(unittest.TestCase):
 class AuditOutboxTests(unittest.TestCase):
     def test_outbox_enqueues_governed_event_and_dispatches_pending_rows(self) -> None:
         engine = create_engine("sqlite:///:memory:")
+        self.addCleanup(engine.dispose)
         Base.metadata.create_all(bind=engine, tables=[AuditOutboxEvent.__table__])
         Session = sessionmaker(bind=engine)
         outbox = SqlAuditOutbox()
@@ -63,6 +64,7 @@ class AuditOutboxTests(unittest.TestCase):
 
     def test_outbox_records_failed_dispatch_for_retry(self) -> None:
         engine = create_engine("sqlite:///:memory:")
+        self.addCleanup(engine.dispose)
         Base.metadata.create_all(bind=engine, tables=[AuditOutboxEvent.__table__])
         Session = sessionmaker(bind=engine)
         outbox = SqlAuditOutbox()