ci: use clang18 for msan build #6038

Job	Run time
git_checks	5s
format	26s
el8 (el8, icc, mpich)	6m 30s
macos (macos-13, xcode14_2, x64, shared, serial)	6m 49s
el8 (el8, oneapi, mpich)	6m 29s
ubuntu (ubuntu20.04, gcc8, mpich)	6m 30s
macos (macos-14, xcode15_4, arm64, shared, serial)	6m 43s
CodeQL (cpp)	6m 30s
ubuntu (ubuntu20.04, gcc9, mpich)	1s
macos (macos-14, xcode15_4, arm64, static, serial)	5m 26s
ubuntu (ubuntu20.04, gcc10, mpich)	6m 28s
docker (ubuntu-bionic)	6m 33s
ubuntu (ubuntu20.04, clang6, mpich)	6m 32s
windows (win2019, shared, msmpi)	6m 34s
ubuntu (ubuntu20.04, clang10, mpich)	6m 29s
windows (win2022, shared, msmpi)	6m 41s
ubuntu (ubuntu20.04, gcc8, ompi)	6m 29s
windows (win2022, serial, windows-2022, vs2022)	6m 34s
ubuntu (ubuntu20.04, gcc8, serial)	6m 28s
windows (win2022, static, serial, windows-2022, vs2022)	6m 40s
ubuntu (ubuntu20.04, clang6, ompi)	6m 29s
ubuntu (ubuntu20.04, clang6, serial)	6m 29s
ubuntu (ubuntu20.04, gcc8, serial, static)	55s
ubuntu (ubuntu22.04, rocm, serial, build_only)	1s
ubuntu (ubuntu22.04, gcc11, mpich)	1s
contract	1s
build_and_test	1s
	2h 4m 54s

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