Py03 almost stable - help needed!

Python working on stable rust is a big thing, and while it’s achievable via dgrunwald’s rust-cpython, the PyO3 approch is a lot more ergonomic to work with.

But it’s just not quite stable - there’s a few specialisations that need to be got rid of so it works on stable:

I don’t think anyone’s had a go at trying to get rid of these last specialisations yet.
Does anyone fancy taking a crack at it? Feels like we’re so close…