fix and update alectryon #3949

Job	Run time
nix	2m 13s
build (dev, --warnings)	3m 19s
build (9.0)	3m 15s
build (9.1)	3m 22s
quick-build (dev, ubuntu-latest)	3m 23s
quick-build (9.0, ubuntu-latest)	3m 9s
opam-build (9.1, ubuntu-latest)	4m 17s
opam-build (9.0, ubuntu-latest)	4m 17s
opam-build (dev, ubuntu-latest)	4m 17s
quick-build (9.1, ubuntu-latest)	3m 15s
doc-alectryon	14m 56s
doc-timing	1m 48s
coqchk (dev)	1m 55s
coqchk (9.1)	1m 49s
coqchk (9.0)	1m 58s
doc-dep-graphs	7m 23s
install (9.0)	1m 43s
doc-coqdoc	1m 30s
install (dev)	1m 44s
install (9.1)	1m 36s
delete-artifacts	6s
deploy-doc	0s
	1h 11m 15s

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