Missing edge in dependency_graph.py

[fpoli]

The ./docs/dependency-graph/dependency_graph.py does not generate the dependency edge prusti-interface --> prusti-specs.

[Aurel300]

Starting from Python 3.11, there is a built-in tomllib library that we could use instead of manually parsing the TOML file.

[fpoli]

That would be great. We could also check if ./x.py metadata provides all the data that we need. That would be more robust than collecting Cargo.toml files.

[JonasAlaif]

There's also cargo tree