[3.14]gh-75666: idlelib backport of iomenu change (GH-151958)

Author: terryjreedy

Lib/idlelib/idle_test/test_iomenu.py

@@ -23,7 +23,7 @@ def setUpClass(cls):
         cls.root = Tk()
         cls.root.withdraw()
         cls.editwin = EditorWindow(root=cls.root)
-        cls.io = iomenu.IOBinding(cls.editwin)
+        cls.io = cls.editwin.io
 
     @classmethod
     def tearDownClass(cls):