Fix lower bounds

[n-osborne]

No description provided.

[jmid]

A suggestion:
For qcheck we've been bitten in the past by trying to support cross-versions as it quickly becomes messy.
Scenario: "Will ortac-runtime.0.5.0 require ortac-core.0.3.0 or only ortac-core.0.2.0"?
This will largely be wasted effort trying to debug lower bound failures! 😬
A qcheck example of this happening in practice: ocaml/opam-repository#24703

For this reason, I suggest using

  "ortac-core" {= version}

etc. so that ortac-runtime.0.2.0 requires precisely ortac-core.0.2.0 (and so on)
in the interest of saving you from additional pain later 🙂

[jmid]

Both dune and opam support the version variable.
A dune example here: https://github.com/ocaml-multicore/multicoretests/blob/main/dune-project#L35
A (generated) opam example here: https://github.com/ocaml-multicore/multicoretests/blob/main/qcheck-stm.opam#L27
Using it has the advantage of not needing to go around and updating many version numbers on each release 🙂

(edit: inserted missing not 😅)

[n-osborne]

Nice!