Process invoice
POST /self/{shopId}/invoices/{invoiceId}/process
curl \
-X POST https://dev.sellpass.io/self/{shopId}/invoices/{invoiceId}/process \
-H "Authorization: $API_KEY"
curl \
-X POST https://dev.sellpass.io/self/{shopId}/invoices/{invoiceId}/process \
-H "Authorization: $API_KEY"