News file: add news for 3.23.x and 3.24.0 versions
News file: add news for 3.23.x and 3.24.0 versions

Those releases were done in the gnome-3-24 branch, not on master.

GNOME/gtksourceview,GNOME/gtksourceview,uajain/gtksourceview,uajain/gtksourceview,uajain/gtksourceview,GNOME/gtksourceview,GNOME/gtksourceview,uajain/gtksourceview,GNOME/gtksourceview,uajain/gtksourceview,GNOME/gtksourceview,GNOME/gtksourceview,uajain/gtksourceview,GNOME/gtksourceview,GNOME/gtksourceview,uajain/gtksourceview,GNOME/gtksourceview,GNOME/gtksourceview,GNOME/gtksourceview,uajain/gtksourceview,uajain/gtksourceview,GNOME/gtksourceview,uajain/gtksourceview,GNOME/gtksourceview,GNOME/gtksourceview