Fails to build on OCaml 4.13.1

[rwmjones]

File "test/test_kstream.ml", line 175, characters 4-34:
175 |     tap (Buffer.add_char buffer) s |> ignore;
          ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
Error (warning 5 [ignored-partial-application]): this function application is partial,
maybe some arguments are missing.

[rwmjones]

A simple fix was just to ignore the error by changing test/dune to:

- (flags (:standard -w +A-44-48)))
+ (flags (:standard -w +A-5-44-48)))

[aantron]

Thanks! I made the warning flags less aggressive in fc7f1d1. They were a holdover from ocamlbuild days.