Add support for RHEL 8 #28

Job	Run time
cleanup (debian-bullseye)	31s
cleanup (rhel-10)	13s
cleanup (rhel-8)	5s
cleanup (tools-rippled-documentation)	8s
cleanup (tools-rippled-clang-format)	54s
cleanup (debian-bookworm)	31s
cleanup (gcc)	5s
cleanup (rhel-9)	2m 28s
cleanup (ubuntu-jammy)	6s
cleanup (tools-rippled-prettier)	8s
cleanup (tools-rippled-pre-commit)	6s
cleanup (ubuntu-noble)	3m 58s
	9m 13s

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