When trying to build phat with opam 2.0, it complains about the ocaml-version field.
error 32: Field 'ocaml-version:' and variable 'ocaml-version' are deprecated, use a dependency towards the 'ocaml'
package instead for availability, and the 'ocaml:version' package variable for scripts
When trying to build phat with opam 2.0, it complains about the ocaml-version field.