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": "f572581c-9e89-4509-8a19-41596dfa4803",
    "type": "shifts",
    "attributes": {
      "schedule_id": "978c233d-14ab-4b44-9845-4c1881ecc247",
      "rotation_id": "08afe83d-0825-477e-8d93-ed3c085b4b64",
      "user_id": 775,
      "starts_at": "2026-01-08T20:14:53.000-08:00",
      "ends_at": "2026-01-09T04:14:53.000-08:00",
      "is_override": true
    },
    "relationships": {
      "shift_override": {
        "data": {
          "id": "45d09339-9251-4e43-ae73-89966ead5efe",
          "type": "shift_overrides"
        }
      },
      "user": {
        "data": {
          "id": "775",
          "type": "users"
        }
      }
    }
  }
}