curl --request PUT \
  --url 'https://api.stateset.com/api/v1/checkout/{session_id}/shipping-method' \
  --header 'Authorization: Bearer YOUR_API_KEY' \
  --header 'Content-Type: application/json' \
  --data '{}'

{
  "data": {
    "amount": "string",
    "estimated_days": 1,
    "method": "Standard"
  },
  "errors": null,
  "message": null,
  "meta": null,
  "success": true
}