ci: Exclude macos tests below 27.x #459

Job	Run time
build (ubuntu-latest, 26.3, false)	34s
build (ubuntu-latest, 27.2, false)	37s
build (ubuntu-latest, 28.2, false)	38s
build (ubuntu-latest, 29.3, false)	51s
build (macos-latest, 28.2, false)	1m 33s
build (macos-latest, 29.3, false)	1m 42s
build (windows-latest, 26.3, false)	2m 23s
build (windows-latest, 27.2, false)	1m 33s
build (windows-latest, 28.2, false)	56s
build (windows-latest, 29.3, false)	1m 22s
build (ubuntu-latest, snapshot, true)	31s
build (macos-latest, snapshot, true)	1m 44s
build (windows-latest, snapshot, true)	1m 5s
	15m 29s

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