Update pyo3 requirement from 0.20.0 to 0.28.1

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@v0.20.0...v0.28.1)

---
updated-dependencies:
- dependency-name: pyo3
  dependency-version: 0.28.1
  dependency-type: direct:production
...

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

Author: dependabot[bot]

Cargo.toml

@@ -9,4 +9,4 @@ name = "rust_python_extension"
 crate-type = ["cdylib"]
 
 [dependencies]
-pyo3 = { version = "0.20.0", features = ["extension-module"] }
+pyo3 = { version = "0.28.1", features = ["extension-module"] }