Bump protobuf from 5.29.4 to 5.29.5 in /hack/gcp-secret-manager (#69254)

Bumps [protobuf](https://github.com/protocolbuffers/protobuf) from 5.29.4 to 5.29.5.
- [Release notes](https://github.com/protocolbuffers/protobuf/releases)
- [Changelog](https://github.com/protocolbuffers/protobuf/blob/main/protobuf_release.bzl)
- [Commits](protocolbuffers/protobuf@v5.29.4...v5.29.5)

---
updated-dependencies:
- dependency-name: protobuf
  dependency-version: 5.29.5
  dependency-type: direct:production
...

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Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>

Author: dependabot[bot]

hack/gcp-secret-manager/requirements.txt

@@ -11,7 +11,7 @@ grpcio==1.71.0
 grpcio-status==1.71.0
 idna==3.10
 proto-plus==1.26.1
-protobuf==5.29.4
+protobuf==5.29.5
 pyasn1==0.6.1
 pyasn1_modules==0.4.1
 PyYAML==6.0.2