Update a payout

curl --request PATCH \
  --url https://api.introw.io/api/v1/payouts/{id} \
  --header 'Content-Type: application/json' \
  --header 'x-api-key: <api-key>' \
  --data '
{
  "stage": "APPROVED",
  "poNumber": "PO-ACME-2026-Q1"
}
'

{
  "data": {
    "id": "pay_2x7n4q8z0w1a2b3c4d5e6f7g",
    "partner": {
      "id": "ptn_01HVK6Y8Z8Q7J8J8J8J8J8J8J8",
      "name": "Acme Partners"
    },
    "batchId": "pbt_9h8g7f6e5d4c3b2a1z0w9v8u",
    "periodStart": "2026-01-01T00:00:00.000Z",
    "periodEnd": "2026-03-31T23:59:59.000Z",
    "amount": {
      "value": "4250.00",
      "currency": "USD"
    },
    "stage": "APPROVED",
    "poNumber": "PO-ACME-2026-Q1",
    "createdAt": "2026-04-05T09:00:00.000Z",
    "updatedAt": "2026-04-08T14:30:00.000Z"
  }
}