Git Search Criteria show_oldest_first wrong documented order of precidence

[jeffbearer]

The search criteria model says that if you use show_oldest_first it ignores item_version. but in testing it's the other way around, it itself is ignored if you also include item_version. Ommiting item_version allows it to work.

https://github.com/microsoft/azure-devops-python-api/blob/451cade4c475482792cbe9e522c1fee32393139e/azure-devops/azure/devops/v6_0/git/models.py#L1959