Bump protobuf from 3.12.2 to 3.18.3 in /python-conda

Bumps [protobuf](https://github.com/protocolbuffers/protobuf) from 3.12.2 to 3.18.3.
- [Release notes](https://github.com/protocolbuffers/protobuf/releases)
- [Changelog](https://github.com/protocolbuffers/protobuf/blob/main/generate_changelog.py)
- [Commits](protocolbuffers/protobuf@v3.12.2...v3.18.3)

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

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

python-conda/requirements.txt

@@ -197,7 +197,7 @@ progressbar==2.5
 promise==2.3
 prometheus-client==0.7.1
 prompt-toolkit==3.0.3
-protobuf==3.12.2
+protobuf==3.18.3
 psutil==5.7.0
 ptyprocess==0.6.0
 py==1.8.0