Constrain js_of_ocaml for Lwt 4.0.0

[aantron]

cc @hannesm @hhugo

Constraints are based on looking in the git history of js_of_ocaml. The dependency on lwt.log first appeared in 2.3, and seems not to be guarded by its own condition.

EDIT: see #11708 (comment).

[camelus]

✅ All lint checks passed 55d1073

• These packages passed lint tests: js_of_ocaml-lwt.3.0.1, js_of_ocaml-lwt.3.0.2, js_of_ocaml-lwt.3.0, js_of_ocaml-lwt.3.1.0, js_of_ocaml.2.3, js_of_ocaml.2.4.1, js_of_ocaml.2.4, js_of_ocaml.2.5, js_of_ocaml.2.6, js_of_ocaml.2.7, js_of_ocaml.2.8.1, js_of_ocaml.2.8.2, js_of_ocaml.2.8.3, js_of_ocaml.2.8.4, js_of_ocaml.2.8

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✅ Installability check (8700 → 8700)

[hhugo]

ack

[hannesm]

thanks, I'll merge this. there's an issue discovered by Travis CI:

=-=- Gathering sources =-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=
[ERROR] curl: code 404 while downloading
        http://ocsigen.org/download/lwt-2.4.3.tar.gz
[ocamlfind.1.7.3-1] http://download.camlcity.org/download/findlib-1.7.3.tar.gz downloaded
[menhir.20140422] http://cristal.inria.fr/~fpottier/menhir/menhir-20140422.tar.gz downloaded
[ERROR] The sources of the following couldn't be obtained, aborting:
          - lwt.2.4.3
        (This may be fixed by running 'opam update')

and a local test lead to the same result, lwt-2.4.3.tar.gz is no longer available from that URL //cc @aantron