override cardinality, not order, as mentioned in categories.finite_gr…

…oups.FiniteGroups.ParentMethods.cardinality

src/sage/groups/perm_gps/permgroup.py

@@ -2355,7 +2355,7 @@ def _order(self):
         return Integer(len(unique)).factorial()
 
     @cached_method
-    def order(self):
+    def cardinality(self):
         """
         Return the number of elements of this group.
 
@@ -2391,8 +2391,6 @@ def order(self):
 
         return Integer(self.gap().Size())
 
-    cardinality = order
-
     def random_element(self):
         """
         Return a random element of this group.