cibuild.yml: correctly check for macOS when determining the need of m… #4987

Job	Run time
FreeBSD Debug x86_64	6m 52s
Ubuntu Debug amd64 (gcc)	6m 48s
FreeBSD Release x86_64	9m 26s
Windows Debug x64 (msvc)	6m 17s
Windows Debug x86 (msvc)	6m 1s
OpenBSD Debug x86_64	11m 35s
Ubuntu Release amd64 (gcc)	6m 41s
Windows Mixed x64 (msvc)	5m 45s
OpenBSD Release x86_64	10m 15s
Ubuntu Debug amd64 (clang)	7m 33s
Windows Mixed x86 (msvc)	5m 17s
NetBSD Debug x86_64	10m 48s
Ubuntu Release amd64 (clang)	9m 33s
Windows Release x64 (msvc)	10m 13s
NetBSD Release x86_64	9m 29s
Alpine Debug x86_64 (gcc)	6m 53s
Windows Release x86 (msvc)	9m 46s
Alpine Release x86_64 (gcc)	8m 54s
Windows Release Master Gold x64 (msvc)	9m 21s
Alpine Debug x86 (gcc)	7m 3s
Alpine Release x86 (gcc)	9m 10s
Fedora Debug x86_64 (gcc)	17m 10s
Windows Release Master Gold x86 (msvc)	8m 30s
Fedora Release x86_64 (gcc)	15m 38s
macOS 13 Debug x86_64 (clang)	7m 33s
macOS 13 Release x86_64 (clang)	8m 49s
macOS 14 Debug arm64 (clang)	5m 3s
macOS 14 Release arm64 (clang)	5m 36s
macOS 15 Debug arm64 (clang)	4m 13s
macOS 15 Release arm64 (clang)	5m 9s
	4h 11m 21s

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