Set usable default parameters

Closes #128 (closed)

arkindex_worker/worker/training.py

@@ -167,8 +167,8 @@ class TrainingMixin(object):
     def update_model_version(
         self,
         model_version_details: dict,
-        description: str = None,
-        configuration: dict = None,
+        description: str = "",
+        configuration: dict = {},
         tag: str = None,
     ) -> None:
         """