cohttp_async_websocket need cohttp < 6

[Kakadu]

check.ci.ocaml.org tries to install cohttp-async.6.0.0~beta2 and gets an error:

 Error: Modules do not match:
        sig
          module IO = Cohttp_async__Io.IO
          module Request = Cohttp_async.Io.Request
          module Response = Cohttp_async.Io.Response
        end
      is not included in Cohttp__.S.IO
      The type "t" is required but not provided
      File "cohttp/src/s.ml", line 23, characters 2-12: Expected declaration
      The value ">>=" is required but not provided

I beleive version constraints were setup incorreclty before:

➜  ~ dpkg --compare-versions 6.0.0~beta2  lt 6 && echo true || echo false
false
➜  ~ dpkg --compare-versions 6.0.0~beta2  lt 6.0.0 && echo true || echo false
true

[mseri]

Thanks