ci: Bump Emacs 29.x to 3 #42

Job	Run time
test (ubuntu-latest, 26.3, false)	35s
test (ubuntu-latest, 27.2, false)	28s
test (ubuntu-latest, 28.2, false)	31s
test (ubuntu-latest, 29.3, false)	33s
test (macos-latest, 26.3, false)	1m 45s
test (macos-latest, 27.2, false)	1m 53s
test (macos-latest, 28.2, false)	2m 0s
test (macos-latest, 29.3, false)	1m 46s
test (windows-latest, 26.3, false)	1m 15s
test (windows-latest, 27.2, false)	1m 1s
test (windows-latest, 28.2, false)	36s
test (windows-latest, 29.3, false)	46s
test (ubuntu-latest, snapshot, true)	29s
test (macos-latest, snapshot, true)	2m 16s
test (windows-latest, snapshot, true)	1m 58s
	17m 52s

Provide feedback