ci: Bump Emacs 29.x to 3 #22

Job	Run time
test (ubuntu-latest, 26.3, false)	29s
test (ubuntu-latest, 27.2, false)	31s
test (ubuntu-latest, 28.2, false)	27s
test (ubuntu-latest, 29.3, false)	43s
test (macos-latest, 26.3, false)	1m 39s
test (macos-latest, 27.2, false)	1m 33s
test (macos-latest, 28.2, false)	1m 32s
test (macos-latest, 29.3, false)	2m 8s
test (windows-latest, 26.3, false)	1m 18s
test (windows-latest, 27.2, false)	48s
test (windows-latest, 28.2, false)	42s
test (windows-latest, 29.3, false)	50s
test (ubuntu-latest, snapshot, true)	28s
test (macos-latest, snapshot, true)	2m 11s
test (windows-latest, snapshot, true)	47s
	16m 6s

Provide feedback