Depend on pyo3 version that supports Python 3.12

[adrian-zon]

Pull Request Check List

• [ ] Added tests for changed code.
• [ ] Updated documentation for changed code.

pyo3 0.20.0 is the first version to actually support Python 3.12.0, see changelog.

[codspeed-hq[bot]]

CodSpeed Performance Report

Merging #848 will not alter performance

_{Comparing adrian-zon:bump_pyo3 (7c3d4ce) with master (b84b976)}

Summary

✅ 1 untouched benchmarks

[Secrus]

Please rebase your changes with master to fix the failing pipeline