bpo-33924: Change IDLE mainmenu.menudefs key 'windows' to 'window' (GH-7836)


Every other menudef key is the lowercase version of the
corresponding main menu entry (in this case, 'Window').
(cherry picked from commit 33c7420e7dd9d8e5b2aa15e98da6291bab6fcf33)

Co-authored-by: Terry Jan Reedy <tjreedy@udel.edu>
diff --git a/Lib/idlelib/pyshell.py b/Lib/idlelib/pyshell.py
index 6746489..52c11e3 100755
--- a/Lib/idlelib/pyshell.py
+++ b/Lib/idlelib/pyshell.py
@@ -852,7 +852,7 @@
         ("edit", "_Edit"),
         ("debug", "_Debug"),
         ("options", "_Options"),
-        ("windows", "_Window"),
+        ("window", "_Window"),
         ("help", "_Help"),
     ]