refactor(devices): update device payment status in background task and remove unused serializer field 🔨

billing/tasks.py

@@ -72,6 +72,9 @@ def update_expired_payments(timestamp: int):
         logger.info(f"Found {count} payments to expire.")
 
         for payment in expired_payments_qs:
+            for device in payment.devices.all():
+                device.has_a_pending_payment = False
+                device.save()
             if (
                 payment.user
                 and payment.user.mobile