feat(lab-3897): add default return when using update project workflow

Author: florianlega

src/kili/adapters/kili_api_gateway/project_workflow/operations_mixin.py

@@ -28,11 +28,7 @@ def update_project_workflow(
         """Update properties in a project workflow."""
         project_workflow_input = project_input_mapper(data=project_workflow_data)
 
-        fields = tuple(
-            name
-            for name, val in project_workflow_input.items()
-            if val is not None and name != "steps"
-        )
+        fields = ["enforceStepSeparation", "steps{id}"]
         fragment = fragment_builder(fields)
         mutation = get_update_project_workflow_mutation(fragment)