ci: Exclude macos tests below 27.x #88

Job	Run time
test (ubuntu-latest, 26.3, false)	38s
test (ubuntu-latest, 27.2, false)	30s
test (ubuntu-latest, 28.2, false)	33s
test (ubuntu-latest, 29.3, false)	37s
test (macos-latest, 28.2, false)	1m 10s
test (macos-latest, 29.3, false)	1m 32s
test (windows-latest, 26.3, false)	2m 21s
test (windows-latest, 27.2, false)	1m 7s
test (windows-latest, 28.2, false)	37s
test (windows-latest, 29.3, false)	1m 8s
test (ubuntu-latest, snapshot, true)	27s
test (macos-latest, snapshot, true)	1m 8s
test (windows-latest, snapshot, true)	1m 10s
	12m 58s

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