Retrieves minimum and maximum voucher amounts

curl --request GET \
  --url https://staging-vouchers.ventogram.com/api/v1/voucher-min-max

{
  "success": true,
  "message": "<string>",
  "data": {
    "NGN": {
      "min": 500,
      "max": 2000000
    },
    "USD": {
      "min": 100,
      "max": 2000
    }
  }
}