curl --request POST \
  --url https://api.portable.io/v2/workflows/{id}/webhooks \
  --header 'Authorization: Bearer <token>' \
  --header 'Content-Type: application/json' \
  --data '
{
  "provider": "slack",
  "credential_source_id": 123,
  "event_type": "<string>"
}
'

{
  "data": {
    "id": 123,
    "webhook_id": "<string>",
    "workflow_id": 123,
    "provider": "slack",
    "url": "<string>",
    "status": "active",
    "trigger_count": 123,
    "credential_source_id": 123,
    "created_at": "2023-11-07T05:31:56Z",
    "event_type": "<string>",
    "last_triggered_at": "2023-11-07T05:31:56Z"
  }
}