fixed bug that caused quman test to fail because the temporary directory is missing

work related to [https://bugzilla.ipr.univ-rennes.fr/show_bug.cgi?id=3093]

test/test_quman.py

@@ -17,6 +17,7 @@ class QumanTestCase(unittest.TestCase):
     def test_quman(self):
         logging.info('test_quman')
         db_path = Path('./quman_test/quman.sqlite')
+        db_path.parent.mkdir(exist_ok=True)
         if db_path.exists():
             db_path.unlink()
         db_backend = SqliteDb(db_path)