All linux CI machines have gtk3 installed. And Python GTK things are too complicate to setup. Change-Id: I3c0d967f61aebea508784df79569b9d0064f66e2 Reviewed-by: Tor Arne Vestbø <tor.arne.vestbo@qt.io> (cherry picked from commit aef55501bccd52f63a84228cb2ee201ec4f5c301) Reviewed-by: Liang Qi <liang.qi@qt.io>