Bump actions/checkout from 5.0.0 to 6.0.1 (#986) #6

Job	Run time
id_repo	4s
lint	39s
docker-build (oldest, cpu)	2m 6s
docker-build (latest, cpu)	2m 50s
docker-build (oldest, hip)	11m 7s
docker-build (latest, cuda)	4m 41s
docker-build (latest, hip)	8m 32s
docker-build (oldest, cuda)	4m 59s
coverage-test (latest, cpu, gcc, g++, 17)	19m 20s
test-with-sanitizer	0s
clang-tidy-test	0s
test	0s
	54m 18s

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