Update RetrospectiveProcessGroup Step

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

{
  "data": {
    "id": "6f645a55-c170-46be-a2a7-ad4ea5f9846d",
    "type": "retrospective_process_group_steps",
    "attributes": {
      "retrospective_process_group_id": "e9d272db-90e6-4835-b2e8-9320ed59c660",
      "retrospective_step_id": "342d1a3d-1350-4c75-aefc-43ac42b56a4d",
      "position": 2,
      "updated_at": "2026-01-26T12:19:47.544-08:00",
      "created_at": "2026-01-26T12:19:47.499-08:00"
    }
  }
}