Fix uninitialized global _pycaosdbconf in configuration.py

src/linkahead/configuration.py

@@ -39,6 +39,8 @@ from os.path import expanduser, isfile, join
 
 from typing import Dict, Union, Callable, Optional
 
+_pycaosdbconf = ConfigParser(allow_no_value=False)
+
 
 def _reset_config():
     global _pycaosdbconf