ci: collect code coverage for install tests #229

Job	Run time
install (debian:bullseye-slim)	22s
unittest (debian:bullseye-slim)	30s
install (debian:bookworm-slim)	28s
system-testing (debian:unstable-slim)	3m 41s
unittest (debian:bookworm-slim)	29s
install (debian:testing-slim)	27s
yamllint	10s
system-testing (ubuntu:jammy)	4m 5s
unittest (debian:testing-slim)	33s
system-testing (ubuntu:mantic)	3m 49s
install (debian:unstable-slim)	26s
unittest (debian:unstable-slim)	36s
install (ubuntu:jammy)	23s
unittest (ubuntu:jammy)	34s
install (ubuntu:mantic)	25s
unittest (ubuntu:mantic)	29s
	17m 27s

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