`Stream` module no longer available in OCaml 5

[patricoferris]

Hi :)) Thanks for the great library!

I'm doing some work with OCaml 5 and since ocaml/ocaml#10896 the Stream library now needs to be explicitly pulled in via https://github.com/ocaml/camlp-streams (which I did quickly patricoferris@21e981f) but I wasn't sure if this is the approach you wanted to go for (maybe vendoring your own Stream for eml or something like that?).

Anyway just thought I'd report it as I couldn't see any other issues/PRs open for it.

[aantron]

Thanks :)

I'd be happy to merge that diff as part of a PR!