Add Patoline support, requires a way to run in CI

[alerque]

Patoline doesn't appear to be too easy to spin up in CI. Neither Arch Linux nor Nix have packages. I started playing around with Arch packaging so I can test it locally and ran into problems because it's dependency chain won't build on OCAML 5. Nix is going to have the same issue.

We might be able to work up something with a Docker container with old libraries, but I'm not looking forward to that route. It would be better if the bulid and packaging situation just got fixed up properly!

To that end I've opened an upstream issue: https://github.com/patoline/patoline/issues/30