bpo-24813: IDLE: Add default title to help_about (#2366)

Patch by Cheryl Sabella.
diff --git a/Lib/idlelib/macosx.py b/Lib/idlelib/macosx.py
index d4566cd..d85278a 100644
--- a/Lib/idlelib/macosx.py
+++ b/Lib/idlelib/macosx.py
@@ -165,7 +165,7 @@
         "Handle Help 'About IDLE' event."
         # Synchronize with editor.EditorWindow.about_dialog.
         from idlelib import help_about
-        help_about.AboutDialog(root, 'About IDLE')
+        help_about.AboutDialog(root)
 
     def config_dialog(event=None):
         "Handle Options 'Configure IDLE' event."