ci: Exclude macos tests below 27.x #188

Job	Run time
test (ubuntu-latest, 26.3, false)	32s
test (ubuntu-latest, 27.2, false)	30s
test (ubuntu-latest, 28.2, false)	29s
test (ubuntu-latest, 29.3, false)	56s
test (macos-latest, 28.2, false)	1m 15s
test (macos-latest, 29.3, false)	1m 14s
test (windows-latest, 26.3, false)	5m 17s
test (windows-latest, 27.2, false)	1m 4s
test (windows-latest, 28.2, false)	1m 2s
test (windows-latest, 29.3, false)	45s
test (ubuntu-latest, snapshot, true)	25s
test (macos-latest, snapshot, true)	1m 7s
test (windows-latest, snapshot, true)	1m 54s
	16m 30s

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