Updating dependencies of problem-specifications

This is probably not controversial, but I need three approving reviews. The problem-spec repo has a dependency flagged for security vulnerabilities. Probably not actually relevant for us, but there won’t be a better opportunity to update.

Here’s the PR:

I’m not gonna lie, the fact that I’m migrating between incompatible versions of a type system built on top of JSON with insecure tooling had me question my life choices a little bit. Had to rewrite it in Rust to regain my sanity :joy: