CI: keep Rust and Python binding versions in sync

[akissinger]

It's a bit confusing to have two separate versions for the Rust crate and the Python bindings. So far, I've been manually nudging them to keep the versions in sync, but I think it would be better to just increment the versions for both if (breaking/non-breaking) changes happen anywhere in the repo.

The only case where this might not be desirable is where we end up pushing the crate version when we've only made changes purely to the Python bindings. However, this will probably be fairly rare, and doesn't bother me as much as having the version number on pip out of sync with the one on crates.io.

attn: @ABorgna