Lockfile for python bindings

[vgel]

As Martin pointed out in #14 , we should have dependabot and a lockfile for the Python bindings part of the crate, since that produces a built artifact (quickdna.so). But since we don't want that for the Rust part which is meant to be consumed as a regular Rust library (https://doc.rust-lang.org/cargo/guide/cargo-toml-vs-cargo-lock.html), we probably want two separate crates that aren't in a workspace so that only one has a lockfile, or something like that.