#150: Ensure list flatten always returns the list in the same order

- That function would return the elements of a list in different order each time (despite identical inputs each time) so this could prove more difficult to test

datagateway_api/common/icat/query.py

@@ -329,4 +329,4 @@ def flatten_query_included_fields(self, includes):
             ICAT query
         """
 
-        return [m for n in (field.split(".") for field in includes) for m in n]
+        return [m for n in (field.split(".") for field in sorted(includes)) for m in n]