Bump protocolbuffers/protobuf from 28.3 to 29.0

Bumps [protocolbuffers/protobuf](https://github.com/protocolbuffers/protobuf) from 28.3 to 29.0.
- [Release notes](https://github.com/protocolbuffers/protobuf/releases)
- [Changelog](https://github.com/protocolbuffers/protobuf/blob/main/protobuf_release.bzl)
- [Commits](protocolbuffers/protobuf@v28.3...v29.0)

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

Signed-off-by: dependabot[bot] <[email protected]>

.github/workflows/protoc-dependabot-hack.yml

@@ -16,4 +16,4 @@ jobs:
 
       # update the version in these places manually when Dependabot proposes a change to it here:
       # 1. the version in main.yml used to install protoc
-      - uses: protocolbuffers/protobuf@v28.3
+      - uses: protocolbuffers/protobuf@v29.0