chore: bump protobuf from 5.29.5 to 5.29.6 in /libs/rag-core-lib

Bumps [protobuf](https://github.com/protocolbuffers/protobuf) from 5.29.5 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: indirect
...

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Author: dependabot[bot]