ci: Exclude macos tests below 27.x #29

Job	Run time
test (ubuntu-latest, 26.3, false)	32s
test (ubuntu-latest, 27.2, false)	27s
test (ubuntu-latest, 28.2, false)	30s
test (ubuntu-latest, 29.3, false)	1m 21s
test (macos-latest, 28.2, false)	1m 13s
test (macos-latest, 29.3, false)	1m 47s
test (windows-latest, 26.3, false)	4m 28s
test (windows-latest, 27.2, false)	2m 38s
test (windows-latest, 28.2, false)	1m 37s
test (windows-latest, 29.3, false)	1m 3s
test (ubuntu-latest, snapshot, true)	23s
test (macos-latest, snapshot, true)	1m 7s
test (windows-latest, snapshot, true)	3m 36s
	20m 42s

Provide feedback