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>
7 files changed