Bump @google-cloud/functions-framework in /scripts/gcb2slack (#3465)

Bumps [@google-cloud/functions-framework](https://github.com/GoogleCloudPlatform/functions-framework-nodejs) from 3.3.0 to 3.4.0.
- [Release notes](https://github.com/GoogleCloudPlatform/functions-framework-nodejs/releases)
- [Changelog](https://github.com/GoogleCloudPlatform/functions-framework-nodejs/blob/main/CHANGELOG.md)
- [Commits](GoogleCloudPlatform/functions-framework-nodejs@v3.3.0...v3.4.0)

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

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