Bump @google-cloud/storage from 6.2.2 to 6.4.2 in /functions

Bumps [@google-cloud/storage](https://github.com/googleapis/nodejs-storage) from 6.2.2 to 6.4.2.
- [Release notes](https://github.com/googleapis/nodejs-storage/releases)
- [Changelog](https://github.com/googleapis/nodejs-storage/blob/main/CHANGELOG.md)
- [Commits](googleapis/nodejs-storage@v6.2.2...v6.4.2)

---
updated-dependencies:
- dependency-name: "@google-cloud/storage"
  dependency-type: direct:production
  update-type: version-update:semver-minor
...

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