Update protobuf requirement in /src/bindings/python

Updates the requirements on [protobuf](https://github.com/protocolbuffers/protobuf) to permit the latest version.
- [Release notes](https://github.com/protocolbuffers/protobuf/releases)
- [Changelog](https://github.com/protocolbuffers/protobuf/blob/main/generate_changelog.py)
- [Commits](https://github.com/protocolbuffers/protobuf/commits)

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

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

src/bindings/python/requirements_test.txt

@@ -38,5 +38,5 @@ retrying
 tox
 types-pkg_resources
 wheel>=0.38.1
-protobuf~=3.18.1
+protobuf~=4.21.12
 numpy>=1.16.6,<=1.23.4