The [opam release](https://github.com/ocaml/opam-repository/pull/10869)
was failing in a way that seemed related to Menhir. Only on linux though
- and it wasn't being caught in our own CI - only OPAM's. Must be for
some configuration we don't test. Making menhir dep more liberal to see
if it will fix our attempted release.
Summary:
Test Plan:
Reviewers:
CC: