List retrospective processes

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

{
  "data": [
    {
      "id": "<string>",
      "type": "retrospective_processes",
      "attributes": {
        "name": "<string>",
        "description": "<string>",
        "is_default": true,
        "created_at": "<string>",
        "updated_at": "<string>",
        "retrospective_process_matching_criteria": {
          "severity_ids": [
            "<string>"
          ]
        }
      }
    }
  ],
  "links": {
    "self": "<string>",
    "first": "<string>",
    "prev": "<string>",
    "next": "<string>",
    "last": "<string>"
  }
}