Update an override shift

curl --request PUT \
  --url https://api.rootly.com/v1/override_shifts/{id} \
  --header 'Authorization: Bearer <token>' \
  --header 'Content-Type: application/vnd.api+json' \
  --data '
{
  "data": {
    "type": "shifts",
    "attributes": {
      "user_id": 123
    }
  }
}
'

{
  "data": {
    "id": "d0ca0ba1-0c8a-4bd9-a2c6-085581d470a0",
    "type": "shifts",
    "attributes": {
      "schedule_id": "dc032949-f2bc-4948-9a45-e6581ce20e61",
      "rotation_id": "c71e6d84-9737-4abf-8fc6-ab7cb1178541",
      "user_id": 794,
      "starts_at": "2026-01-22T21:21:26.000-08:00",
      "ends_at": "2026-01-23T05:21:26.000-08:00",
      "is_override": true
    },
    "relationships": {
      "shift_override": {
        "data": {
          "id": "4dfdf27d-4756-4d9b-826c-35fce77adbe9",
          "type": "shift_overrides"
        }
      },
      "user": {
        "data": {
          "id": "794",
          "type": "users"
        }
      }
    }
  }
}