x11-wm/cosmic-comp: update to 1.0.0.a.5.1

Changes: https://github.com/pop-os/cosmic-comp/compare/epoch-1.0.0-alpha.5...epoch-1.0.0-alpha.5.1
Reported by: Repology

(cherry picked from commit b71e4f0d22ead3c7d43f94e558812301c0fa6d9d)