Retrieves an incident retrospective step

curl --request GET \
  --url https://api.rootly.com/v1/incident_retrospective_steps/{id} \
  --header 'Authorization: Bearer <token>'

{
  "data": {
    "id": "4aaa8ea6-d073-4148-b0ac-7f8864678977",
    "type": "incident_retrospective_steps",
    "attributes": {
      "retrospective_step_id": "1f338d00-3a77-4937-bff0-a754625afd84",
      "incident_id": "7e27d35d-4fc7-40a7-9abf-6dc2e86bfa09",
      "title": "Step 4",
      "description": null,
      "due_date": null,
      "user_id": null,
      "kind": "custom",
      "position": 1,
      "skippable": false,
      "status": "todo",
      "status_changed_at": null,
      "status_changed_by_id": null,
      "created_at": "2025-11-03T21:35:15.084-08:00",
      "updated_at": "2025-11-03T21:35:15.084-08:00"
    }
  }
}