Add an upper-bound constraint on OCaml

[kit-ty-kate]

odoc doesn't currently have an upper-bound constraint on its dependency towards OCaml. However it's a near certainty that it will be broken by the next version of the compiler.

To avoid myself and others having to do double the work in opam-repository (e.g. ocaml/opam-repository#26640) I would encourage you to add the upper-bound constraints on your packages in both master and 2.4 branch

[kit-ty-kate]

Thanks! Could it be backported to the 2.4 branch as well just in case?

[Julow]

Yes: #1201
Thanks for the issue :)

[kit-ty-kate]

ah sorry i missed that PR. Thanks!