x11-wm/cosmic-comp: update to 1.0.0.a.4

Changes: https://github.com/pop-os/cosmic-comp/compare/epoch-1.0.0-alpha.3...epoch-1.0.0-alpha.4
Reported by: Phoronix

(cherry picked from commit 9131d6a27c73a3fa27aec54a05030cb48264169e)