Retrieves an incident retrospective step

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

{
  "data": {
    "id": "21e4a664-1626-4c40-be2f-bf8059956e61",
    "type": "incident_retrospective_steps",
    "attributes": {
      "retrospective_step_id": "a81e65c5-e96d-4a3d-8fe8-5927412b5b96",
      "incident_id": "17094bfc-98c3-4c97-854e-003093c447ba",
      "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": "2026-01-23T22:58:11.172-08:00",
      "updated_at": "2026-01-23T22:58:11.172-08:00"
    }
  }
}