Mirage: Emile should not be a dependency of dream-mirage

[aantron]

From #249 (comment):

It's a bit unfortunate 😕 . Currently, only paf-le (which is another package to handle Let's encrypt certificates) depends on emile. Not sure which direction you want to take, but if you don't use paf-le and Let's encrypt certificate, you should not have such dependency.

cc @dinosaure

[dinosaure]

Actually, into the last version of paf (0.5.0), we removed the paf-le package (and integrate it directly on ocaml-letsencrypt). That mostly means that the last distribution/release of paf does not require emile anymore. I advise you to upgrade paf on your side and emile will be deleted magically 👍.