Bump com.google.cloud:libraries-bom in /modules/gcloud

Bumps [com.google.cloud:libraries-bom](https://github.com/googleapis/java-cloud-bom) from 26.72.0 to 26.79.0.
- [Release notes](https://github.com/googleapis/java-cloud-bom/releases)
- [Commits](https://github.com/googleapis/java-cloud-bom/compare/v26.72.0...v26.79.0)

---
updated-dependencies:
- dependency-name: com.google.cloud:libraries-bom
  dependency-version: 26.79.0
  dependency-type: direct:production
  update-type: version-update:semver-minor
...

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