Bump protobuf from 3.6.1 to 4.22.0

Bumps [protobuf](https://github.com/protocolbuffers/protobuf) from 3.6.1 to 4.22.0.
- [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/compare/v3.6.1...v4.22.0)

---
updated-dependencies:
- dependency-name: protobuf
  dependency-type: direct:production
  update-type: version-update:semver-major
...

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

requirements.txt

@@ -15,7 +15,7 @@ idna==2.7
 isort==4.3.4
 lazy-object-proxy==1.3.1
 mccabe==0.6.1
-protobuf==3.6.1
+protobuf==4.22.0
 pyasn1-modules==0.2.2
 pyasn1==0.4.4
 pylint==2.1.1