Bump protobuf from 3.20.3 to 5.29.6 in /experiment

Bumps [protobuf](https://github.com/protocolbuffers/protobuf) from 3.20.3 to 5.29.6.
- [Release notes](https://github.com/protocolbuffers/protobuf/releases)
- [Commits](https://github.com/protocolbuffers/protobuf/commits)

---
updated-dependencies:
- dependency-name: protobuf
  dependency-version: 5.29.6
  dependency-type: direct:production
...

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

Author: dependabot[bot]

experiment/requirements.txt

@@ -7,7 +7,7 @@ keras==2.15.0
 keras-tuner==1.4.7
 numpy==1.26.4
 onnx==1.17.0
-protobuf==3.20.3
+protobuf==5.29.6
 scikit-learn==1.6.1
 tensorflow-cpu==2.15.1
 tf2onnx==1.16.1