update rpds.py for PyO3 0.23

[ngoldbaum]

Opening as a draft because PyO3 0.23 isn't out yet.

Along with accompanying uncommitted Cargo.toml updates, this passes the test suite on the free-threaded Python build.

[Julian]

Thanks! Really appreciated. Adding a CI environment which runs on the free-threaded build would also be nice I think whenever we do merge.

[ngoldbaum]

See Quansight-Labs/free-threaded-compatibility#98 and linked issues if you're curious why I'm using quansight-labs/setup-python instead of the normal Github-maintained one. Hopefully we can switch it back soon.

We probably need to open a followup issue about multithreaded testing, marking the extension module as thread-safe, and uploading free-threaded wheels, but I think this is ready now.

[Julian]

Fantastic thanks again! I'll have a look tomorrow here (and read that linked issue) but this looks great.

(The CI failure is unrelated obviously, I forgot to disable zizmor in pre-commit.ci as it doesn't run there yet, will do that.)