feat(tests): Use subprocess.run #297

Job	Run time
unittest (debian:bookworm-slim)	26s
unittest (debian:testing-slim)	22s
unittest (debian:unstable-slim)	24s
install (debian:bookworm-slim)	19s
unittest (ubuntu:jammy)	27s
system-testing (debian:testing-slim)	2m 30s
skip-linters (debian:bookworm-slim)	23s
install (debian:testing-slim)	18s
system-testing (debian:unstable-slim)	2m 31s
skip-linters (debian:testing-slim)	19s
install (debian:unstable-slim)	21s
system-testing (ubuntu:jammy)	3m 3s
skip-linters (debian:unstable-slim)	19s
install (ubuntu:jammy)	21s
unittest (ubuntu:noble)	28s
system-testing (ubuntu:noble)	3m 45s
skip-linters (ubuntu:jammy)	26s
unittest (ubuntu:oracular)	28s
install (ubuntu:noble)	27s
system-testing (ubuntu:oracular)	2m 34s
skip-linters (ubuntu:noble)	28s
install (ubuntu:oracular)	21s
skip-linters (ubuntu:oracular)	44s
yamllint	10s
upload-to-codecov	11s
	22m 5s

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