ci: Exclude macos tests below 28.x #523

Job	Run time
test (ubuntu-latest, 27.2, false)	1m 14s
test (ubuntu-latest, 28.2, false)	1m 31s
test (ubuntu-latest, 29.3, false)	1m 23s
test (macos-latest, 28.2, false)	1m 51s
test (macos-latest, 29.3, false)	2m 34s
test (windows-latest, 27.2, false)	2m 27s
test (windows-latest, 28.2, false)	1m 55s
test (windows-latest, 29.3, false)	2m 32s
test (ubuntu-latest, snapshot, true)	1m 3s
test (macos-latest, snapshot, true)	1m 35s
test (windows-latest, snapshot, true)	35s
	18m 40s

Provide feedback