3.4.0

CHANGES:

• Fix several issues on git-unix (@dinosaure, @sternenseemann, #488)
• Fix set of references by git-unix (@dinosaure, @jnavila, #490, #489)
• Remove dependency with curl (@dinosaure, #491)
• Provide Git_unix.ctx (@dinosaure, #493)
• Update the plumbing between carton.0.4.1 and git (@dinosaure, #493)
• Expose information used by Git_unix to start a connection (@dinosaure, #498)
• Add missing fmt and logs on several dune files (@craigfe, @dinosaure, #499)
• Be able to pass threads argument when we fetch (@dinosaure, #500)
• Fix documentation on search.ml (@dinosaure, #501)
• Be compatible with alcotest.1.4.0 (@dinosaure, #504)
• Delete mimic from the distribution (now available on https://github.com/dinosaure/mimic)
  (@dinosaure, #505)
• Fix temporary directories on unix tests (@dinosaure, #506)
• Use the non-stream API of decompress for loose objects (@clecat, @dinosaure, #502)
• Use git-paf and paf.0.0.2 instead of CoHTTP (@dinosaure, #508)
• Don't try to download tags implicitely (@dinosaure, #507)
• Fix bug about negotiation over HTTP connection (@dinosaure, #507)