Update test_ast.py

Co-authored-by: Bénédikt Tran <10796600+picnixz@users.noreply.github.com>

Author: brianschubert

Lib/test/test_ast/test_ast.py

@@ -424,7 +424,7 @@ def test_dynamic_attr(self):
                 continue
             if self._is_ast_node(name, item):
                 x = self._construct_ast_class(item)
-                # Random attribute assignment is allowed
+                # Custom attribute assignment is allowed
                 x.foo = 5
                 self.assertEqual(x.foo, 5)
                 del x.foo