Update cart_object.py (#175)

..or change first param on line 33 from checkout_handle to handle

Author: johnniemorrow

patterns-use-cases/ticket-reservation/ticket-reservation-python/example/cart_object.py

@@ -3,7 +3,7 @@
 from restate.context import ObjectContext
 from restate.object import VirtualObject
 
-from example.checkout_service import handle
+from example.checkout_service import handle as checkout_handle
 from example.ticket_object import reserve, mark_as_sold, unreserve
 
 cart = VirtualObject("cart")