Update pyo3 requirement from 0.20.0 to 0.21.2

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@v0.20.0...v0.21.2)

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

Signed-off-by: dependabot[bot] <[email protected]>

Cargo.toml

@@ -10,7 +10,7 @@ publish = false
 lazy_static = "1.4.0"
 thiserror = "1.0.30"
 smallvec = "1.8.0"
-pyo3 = {version = "0.20.0", features = ["extension-module"], optional = true}
+pyo3 = {version = "0.21.2", features = ["extension-module"], optional = true}
 quickcheck = {version = "1.0.3", optional = true}
 serde = {version = "1.0", features = ["derive"], optional = true}