Changes to PATCH /api/inventory/purchaseorder/:id/with-materials

the entries/items/entry_date response's property format changed from date to no format for status 200

the expected_entry_date response's property format changed from date to no format for status 200

added the required property entries/items/entry_date_iso to the response with the 200 status

added the required property expected_entry_date_iso to the response with the 200 status

endpoint added