fix build: bump boost version to 1.18 for Ubuntu 24.04 #13

Job	Run time
ubuntu-22.04: clang-14 + debug + sanitize addr+ub	1h 3m 30s
ubuntu-20.04: g++-9 + release	1h 21m 3s
ubuntu-20.04: g++-8 + debug	1h 7m 5s
	3h 31m 38s

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