Python compatibility checks

Now that Python has grown type support, something like https://mypy.readthedocs.io/en/stable/stubtest.html would be a good way to do the sort of thing libabigail does to check that a new version of a package exposes the same interface as previous versions. (Of course, in both cases, whether it has the same semantics is a different question, but there are a wide variety of tools for writing tests, and no real substitutes to doing so.)