Update tests

Author: ArpitSachan

tests/queryset/test_queryset.py

@@ -2625,9 +2625,6 @@ def test_last(self):
         with pytest.raises(OperationError):
             self.Person.objects.last()
 
-        self.Person(name="User D", age=30).save()
-        assert self.Person.objects.order_by("-age").last() == person3
-
     def test_order_by_optional(self):
         class BlogPost(Document):
             title = StringField()