fix load credentials function

Author: DenisaCG

jupyter_drives/base.py

@@ -73,7 +73,7 @@ def set_default_api_base_url(self):
 
     def __init__(self, **kwargs):
         super().__init__(**kwargs)
-        self.load_credentials()
+        self._load_credentials()
 
     def _load_credentials(self):
         # check if credentials were already set in jupyter_notebook_config.py