ci: Exclude macos tests below 27.x #23

Job	Run time
test (ubuntu-latest, 26.3, false)	31s
test (ubuntu-latest, 27.2, false)	32s
test (ubuntu-latest, 28.2, false)	30s
test (ubuntu-latest, 29.3, false)	40s
test (macos-latest, 28.2, false)	1m 14s
test (macos-latest, 29.3, false)	1m 16s
test (windows-latest, 26.3, false)	3m 44s
test (windows-latest, 27.2, false)	1m 8s
test (windows-latest, 28.2, false)	50s
test (windows-latest, 29.3, false)	1m 3s
test (ubuntu-latest, snapshot, true)	26s
test (macos-latest, snapshot, true)	1m 8s
test (windows-latest, snapshot, true)	2m 12s
	15m 14s

Provide feedback