message: Add support for invoice paid event
diff: @@ -97,6 +97,8 @@ pub enum EventType {
  InvoiceFinalized,
  #[serde(rename = "invoice.marked_uncollectible")]
  InvoiceMarkedUncollectible,
  + #[serde(rename = "invoice.paid")]
  + InvoicePaid,
  #[serde(rename = "invoice.payment_action_required")]
  InvoicePaymentActionRequired,
  #[serde(rename = "invoice.payment_failed")]
  