Widgets: add back erroneously delete unfocused_borders color definition.
Widgets: add back erroneously delete unfocused_borders color definition.

DoctorJellyface/gnome-themes-standard,ChrisCummins/gnome-themes-standard,cosimoc/gnome-themes-standard,rgcjonas/adwaita-semidark,ChrisCummins/gnome-themes-standard,rgcjonas/adwaita-semidark,rgcjonas/adwaita-semidark,magcius/gnome-themes-standard,cosimoc/gnome-themes-standard,rgcjonas/adwaita-semidark,DoctorJellyface/gnome-themes-standard,magcius/gnome-themes-standard,magcius/gnome-themes-standard,cosimoc/gnome-themes-standard,cosimoc/gnome-themes-standard,ChrisCummins/gnome-themes-standard,ChrisCummins/gnome-themes-standard,ChrisCummins/gnome-themes-standard,Distrotech/gnome-themes-standard,Distrotech/gnome-themes-standard