Remove Lang module

[hedayaty]

Feedback from gnome team:
Lang is a deprecated module. Please remove it for the next version:
https://wiki.gnome.org/Projects/GnomeShell/Extensions/Review#General_Advice
Learn how to remove Lang from your code:
https://gjs.guide/guides/gjs/legacy-class-syntax.html

If you need any help with your extension you can ask us on:
GNOME Matrix channel: https://matrix.to/#/#extensions:gnome.org
IRC Bridge: irc://irc.gimpnet.org/shell-extensions