Bump protobuf from 3.17.3 to 3.18.3 in /ICLR2023

Bumps [protobuf](https://github.com/protocolbuffers/protobuf) from 3.17.3 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@v3.17.3...v3.18.3)

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

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

Author: dependabot[bot]

ICLR2023/requirements.txt

@@ -164,7 +164,7 @@ portalocker==1.7.1
 preshed==3.0.5
 promise==2.3
 prompt-toolkit==3.0.20
-protobuf==3.17.3
+protobuf==3.18.3
 psb2==1.0.0
 psutil==5.8.0
 ptyprocess==0.7.0