Handle AUCTeX's new mode naming convention #152

Job	Run time
test (ubuntu-latest, 27.2, false)	47s
test (ubuntu-latest, 28.2, false)	47s
test (ubuntu-latest, 29.2, false)	46s
test (macos-latest, 27.2, false)	2m 38s
test (macos-latest, 28.2, false)	2m 35s
test (macos-latest, 29.2, false)	1m 57s
test (windows-latest, 27.2, false)	1m 22s
test (windows-latest, 28.2, false)	1m 3s
test (windows-latest, 29.2, false)	1m 13s
test (ubuntu-latest, snapshot, true)	39s
test (macos-latest, snapshot, true)	2m 7s
test (windows-latest, snapshot, true)	33s
	16m 27s

Provide feedback