curl --request GET \
  --url https://api.salesbricks.com/api/v2/invoices/{invoice_id} \
  --header 'X-SALESBRICKS-KEY: <api-key>'

{
  "invoice_id": "3c90c3cc-0d44-4b50-8888-8dd25736052a",
  "subscription_id": "3c90c3cc-0d44-4b50-8888-8dd25736052a",
  "customer_id": "3c90c3cc-0d44-4b50-8888-8dd25736052a",
  "invoice_number": "<string>",
  "due_at": "2023-11-07T05:31:56Z",
  "bill_at": "2023-11-07T05:31:56Z",
  "issued_at": "2023-11-07T05:31:56Z",
  "status": "<string>",
  "fully_paid_at": "2023-11-07T05:31:56Z",
  "grand_total": 123,
  "remaining_amount": 123,
  "currency": "<string>",
  "is_renewal_estimate": true
}