fix default dict for json loads (#2414)

json.loads does not work with {}. It needs to be `'{}'` .

Author: iamsgarg-ob

metaflow/plugins/argo/argo_workflows_deployer_objects.py

@@ -277,7 +277,7 @@ def from_deployment(cls, identifier: str, metadata: Optional[str] = None):
 
         flow_name = metadata_annotations.get("metaflow/flow_name", "")
         username = metadata_annotations.get("metaflow/owner", "")
-        parameters = json.loads(metadata_annotations.get("metaflow/parameters", {}))
+        parameters = json.loads(metadata_annotations.get("metaflow/parameters", "{}"))
 
         # these two only exist if @project decorator is used..
         branch_name = metadata_annotations.get("metaflow/branch_name", None)