curl --request POST \
  --url https://api.getlago.com/api/v1/invoices/{lago_id}/payment_url \
  --header 'Authorization: Bearer <token>'

{
  "invoice_payment_details": {
    "lago_customer_id": "1a901a90-1a90-1a90-1a90-1a901a901a90",
    "lago_invoice_id": "1e501a90-1a90-1a90-1a90-1a901a901a80",
    "external_customer_id": "5eb02857-a71e-4ea2-bcf9-57d3a41bc6ba",
    "payment_provider": "stripe",
    "payment_url": "https://foo.bar"
  }
}