remove end_datetime from conditionaloffer fixture
"benefit": 2,
"priority": 0,
"start_datetime": "2018-08-20T00:00:00Z",
- "end_datetime": "2019-03-06T16:45:00Z",
+ "end_datetime": null,
"max_global_applications": null,
"max_user_applications": null,
"max_basket_applications": null,
