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": "c193c8e8-8f03-414d-9322-a38a3ee15bcd",
    "type": "shifts",
    "attributes": {
      "schedule_id": "dd6c6e69-1cdb-4210-80b0-9afeafc31d07",
      "rotation_id": "93faa18a-2552-432c-a68e-8f64623ba022",
      "user_id": 468,
      "starts_at": "2025-12-19T12:17:33.000-08:00",
      "ends_at": "2025-12-19T20:17:33.000-08:00",
      "is_override": true
    },
    "relationships": {
      "shift_override": {
        "data": {
          "id": "2a53b4ef-a487-4c00-891b-7f7d2b5316bb",
          "type": "shift_overrides"
        }
      },
      "user": {
        "data": {
          "id": "468",
          "type": "users"
        }
      }
    }
  }
}