Get billing alert configuration

curl --request GET \
  --url {schemes}://api.upsun.com/organizations/{organization_id}/alerts/billing \
  --header 'Authorization: Bearer <token>'

{
  "id": "<string>",
  "active": true,
  "alerts_sent": 123,
  "last_alert_at": "<string>",
  "updated_at": "<string>",
  "config": {
    "threshold": {
      "formatted": "<string>",
      "amount": 123,
      "currency_code": "<string>",
      "currency_symbol": "<string>"
    },
    "mode": "<string>"
  }
}