Fix broken test on logilab-constraint or restraint the size of this project?

I've discovered that we actually have a library called logilab-constraint used by RQL and no one seems to be aware of it anymore (not work has been done on it since 2015).

And, sadly, tests are broken on it: https://forge.extranet.logilab.fr/open-source/logilab-constraint/-/jobs/26065

I don't know how worth it is it to spent time on it and I'm not sure that much.

I haven't taken the time to inspect how it is used and why and if we can't simply can ditch it.