use get DbRepoConnector creation

fairnb/api/dbrepo.py

@@ -82,12 +82,12 @@ class DBRepoConnector:
     @classmethod
     def from_config(cls, config: dict, credentials: dict):
         return cls(
-            credentials["username"],
-            credentials["password"],
-            credentials["client_secret_key"],
-            config["host"],
+            credentials.get("username"),
+            credentials.get("password"),
+            credentials.get("client_secret_key"),
+            config.get("host"),
             # config["container-id"],
-            config["database-id"]
+            config.get("database-id")
         )
 
     def authenticate(self, username: str = None, password: str = None):