ci: Bump Emacs 29.x to 3 #41

Job	Run time
test (ubuntu-latest, 26.3, false)	27s
test (ubuntu-latest, 27.2, false)	38s
test (ubuntu-latest, 28.2, false)	41s
test (ubuntu-latest, 29.3, false)	46s
test (macos-latest, 26.3, false)	1m 36s
test (macos-latest, 27.2, false)	2m 11s
test (macos-latest, 28.2, false)	2m 9s
test (macos-latest, 29.3, false)	1m 54s
test (windows-latest, 26.3, false)	2m 24s
test (windows-latest, 27.2, false)	1m 14s
test (windows-latest, 28.2, false)	55s
test (windows-latest, 29.3, false)	52s
test (ubuntu-latest, snapshot, true)	37s
test (macos-latest, snapshot, true)	1m 39s
test (windows-latest, snapshot, true)	1m 37s
	19m 40s

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