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": "1889ca35-602f-47b6-930d-099d4c22c51e",
    "type": "shifts",
    "attributes": {
      "schedule_id": "9c54fefc-e944-4660-b30a-1763ff133a86",
      "rotation_id": "c12ad3ea-bcda-4932-95e6-ba7f49881aee",
      "user_id": 881,
      "starts_at": "2026-02-12T21:31:59.000-08:00",
      "ends_at": "2026-02-13T05:31:59.000-08:00",
      "is_override": true
    },
    "relationships": {
      "shift_override": {
        "data": {
          "id": "bcb1c614-3d88-4643-b567-2b9f064baf27",
          "type": "shift_overrides"
        }
      },
      "user": {
        "data": {
          "id": "881",
          "type": "users"
        }
      }
    }
  }
}