fix exceptions related to btcpay HTTP calls. better cleanup of expired

btcpay invoices.

capsulflask/db_model.py

@@ -218,6 +218,10 @@ class DBModel:
     else:
       return None
 
+  def delete_payment_session(self, payment_type, id):
+    self.cursor.execute( "DELETE FROM payment_sessions WHERE id = %s AND type = %s", (id, payment_type) )
+    self.connection.commit()
+
   def btcpay_invoice_resolved(self, id, completed):
     self.cursor.execute("SELECT email, payment_id FROM unresolved_btcpay_invoices WHERE id = %s ", (id,))
     row = self.cursor.fetchone()