deps: update pyo3 requirement from 0.16.5 to 0.20.2

Updates the requirements on [pyo3](https://github.com/pyo3/pyo3) to permit the latest version.
- [Release notes](https://github.com/pyo3/pyo3/releases)
- [Changelog](https://github.com/PyO3/pyo3/blob/main/CHANGELOG.md)
- [Commits](PyO3/pyo3@v0.16.5...v0.20.2)

---
updated-dependencies:
- dependency-name: pyo3
  dependency-type: direct:production
...

Signed-off-by: dependabot[bot] <support@github.com>

Cargo.toml

@@ -21,4 +21,4 @@ crate-type = ["cdylib"]
 decancer = "1.6.4"
 
 # The most beautiful bindings in existence
-pyo3 = { version = "0.16.5", features = ["extension-module"] }
+pyo3 = { version = "0.20.2", features = ["extension-module"] }