6.0.0

CHANGES:

• bump minimum dune version to 3.8 (@avsm)
• cohttp-eio: Use system authenticator in example.
• http, cohttp: remove the scheme field from requests. This means that
  [Request.uri] no longer returns the same URI as was to create the request
  with [Request.make] (@rgrinberg 1086)
• cohttp-eio: Remove unused Client_intf module (talex5 #1081)
• cohttp-eio: Make server response type abstract and allow streaming in cohttp-eio (talex5 #1024)
• cohttp-{lwt,eio}: server: add connection header to response if not present (ushitora-anqou #1025)
• cohttp-curl: Curl no longer prepends the first HTTP request header to the output. (jonahbeckford #1030, #987)
• cohttp-eio: client: use permissive argument type for make_generic
• cohttp-eio: Improve error handling in example server (talex5 #1023)
• cohttp-eio: Don't blow up Server.callback on client disconnections. (mefyl #1015)
• http: Fix assertion in Source.to_string_trim when pos <> 0 (mefyl #1017)
• cohttp: Cohttp.Request.make_for_client no longer allows setting both
  ~chunked:true and ~body_length.
• cohttp-lwt-unix: Don't blow up when certificates are not available and no-network requests are made. (akuhlens #1027)
  • Makes cohttp-lwt.S.default_ctx lazy.