Update vimix-gtk-theme to 20210712
- Fixed: GSConnect: No name when more than one device
- Fixed: Cancel button overlaps unlock button in lightdm
- Remove gnome-shell builddep because the default is latest version.
- Specify what versions of GTK the theme supports
Signed-off-by: Algent Albrahimi <firstname.lastname@example.org>
Test Plan: Change system gtk theme to all Vimix variants.
Reviewers: Triage Team, JoshStrobl
Reviewed By: Triage Team, JoshStrobl
Differential Revision: https://dev.getsol.us/D11463