Bump up requirement for Cogl
Bump up requirement for Cogl

We're going to use API added in Cogl 1.21.

Distrotech/clutter,Distrotech/clutter,jigpu/clutter,jigpu/clutter,GNOME/clutter,jigpu/clutter,jigpu/clutter,Distrotech/clutter,jigpu/clutter,GNOME/clutter,GNOME/clutter,GNOME/clutter,Distrotech/clutter,jigpu/clutter,GNOME/clutter,Distrotech/clutter,Distrotech/clutter