Update Rust crate pyo3 to v0.21.2

[renovate[bot]]

This PR contains the following updates:

Package	Type	Update	Change
pyo3	dependencies	patch	0.21.1 -> 0.21.2

---

Release Notes

pyo3/pyo3 (pyo3)

### [`v0.21.2`](https://togithub.com/pyo3/pyo3/blob/HEAD/CHANGELOG.md#0212---2024-04-16) [Compare Source](https://togithub.com/pyo3/pyo3/compare/v0.21.1...v0.21.2) ##### Changed - Deprecate the `PySet::empty()` gil-ref constructor. [#​4082](https://togithub.com/PyO3/pyo3/pull/4082) ##### Fixed - Fix compile error for `async fn` in `#[pymethods]` with a `&self` receiver and more than one additional argument. [#​4035](https://togithub.com/PyO3/pyo3/pull/4035) - Improve error message for wrong receiver type in `__traverse__`. [#​4045](https://togithub.com/PyO3/pyo3/pull/4045) - Fix compile error when exporting a `#[pyclass]` living in a different Rust module using the `experimental-declarative-modules` feature. [#​4054](https://togithub.com/PyO3/pyo3/pull/4054) - Fix `missing_docs` lint triggering on documented `#[pymodule]` functions. [#​4067](https://togithub.com/PyO3/pyo3/pull/4067) - Fix undefined symbol errors for extension modules on AIX (by linking `libpython`). [#​4073](https://togithub.com/PyO3/pyo3/pull/4073)

---

Configuration

📅 Schedule: Branch creation - At any time (no schedule defined), Automerge - At any time (no schedule defined).

🚦 Automerge: Disabled by config. Please merge this manually once you are satisfied.

♻ Rebasing: Whenever PR becomes conflicted, or you tick the rebase/retry checkbox.

🔕 Ignore: Close this PR and you won't be reminded about this update again.

---

• [ ] If you want to rebase/retry this PR, check this box

---

This PR has been generated by Mend Renovate. View repository job log here.