add: `gamescope-git` #9064

Job	Run time
test-on-ubuntu (ubuntu:latest, master)	8m 16s
test-on-debian (debian:stable, master)	33s
test-on-ubuntu (ubuntu:latest, develop)	7m 33s
test-on-debian (debian:stable, develop)	7m 54s
test-on-ubuntu (ubuntu:devel, master)	7m 18s
test-on-debian (debian:testing, master)	35s
test-on-ubuntu (ubuntu:devel, develop)	6m 51s
test-on-debian (debian:testing, develop)	5m 19s
test-on-ubuntu (ubuntu:rolling, master)	8m 7s
test-on-debian (debian:unstable, master)	36s
test-on-ubuntu (ubuntu:rolling, develop)	7m 30s
test-on-debian (debian:unstable, develop)	5m 49s
	1h 6m 21s

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