build(deps): update pyo3-build-config requirement from 0.20.0 to 0.21.0

Updates the requirements on [pyo3-build-config](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...v0.21.0)

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

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

rustsat/Cargo.toml

@@ -34,7 +34,7 @@ pyo3 = { version = "0.20.0", optional = true, features = [
 
 [build-dependencies]
 cbindgen = "0.26.0"
-pyo3-build-config = { version = "0.20.0", optional = true }
+pyo3-build-config = { version = "0.21.0", optional = true }
 
 [dev-dependencies]
 inline-c = "0.1.7"