ci: use clang18 for msan build #6042

Job	Run time
git_checks	8s
format	29s
el8 (el8, icc, mpich)	13m 29s
macos (macos-13, xcode14_2, x64, shared, serial)	13m 46s
el8 (el8, oneapi, mpich)	13m 30s
ubuntu (ubuntu20.04, gcc8, mpich)	9m 18s
macos (macos-14, xcode15_4, arm64, shared, serial)	8m 37s
CodeQL (cpp)	13m 34s
ubuntu (ubuntu20.04, gcc9, mpich)	6m 4s
macos (macos-14, xcode15_4, arm64, static, serial)	4m 50s
ubuntu (ubuntu20.04, gcc10, mpich)	13m 26s
docker (ubuntu-bionic)	7m 16s
ubuntu (ubuntu20.04, clang6, mpich)	7m 42s
windows (win2019, shared, msmpi)	13m 34s
ubuntu (ubuntu20.04, clang10, mpich)	13m 27s
windows (win2022, shared, msmpi)	13m 33s
ubuntu (ubuntu20.04, gcc8, ompi)	13m 27s
ubuntu (ubuntu20.04, gcc8, serial)	13m 27s
windows (win2022, serial, windows-2022, vs2022)	12m 45s
ubuntu (ubuntu20.04, clang6, ompi)	13m 26s
windows (win2022, static, serial, windows-2022, vs2022)	13m 33s
ubuntu (ubuntu20.04, clang6, serial)	11m 51s
ubuntu (ubuntu20.04, gcc8, serial, static)	8m 34s
ubuntu (ubuntu22.04, rocm, serial, build_only)	1m 30s
ubuntu (ubuntu22.04, gcc11, mpich)	4m 3s
contract (examples)	2m 1s
contract (lammps)	2m 37s
contract (tau)	5m 41s
build_and_test	1s
	4h 15m 39s

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