x11-wm/cosmic-comp: update to 1.0.0.b.7

Changes: https://github.com/pop-os/cosmic-comp/compare/epoch-1.0.0-beta.6...epoch-1.0.0-beta.7
Reported by: Repology

(cherry picked from commit 6e032f810edb28a211b8a0bec5f102dadd6b85bf)