Bump @google-cloud/pubsub from 2.19.0 to 3.4.1

Bumps [@google-cloud/pubsub](https://github.com/googleapis/nodejs-pubsub) from 2.19.0 to 3.4.1.
- [Release notes](https://github.com/googleapis/nodejs-pubsub/releases)
- [Changelog](https://github.com/googleapis/nodejs-pubsub/blob/main/CHANGELOG.md)
- [Commits](https://github.com/googleapis/nodejs-pubsub/compare/v2.19.0...v3.4.1)

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

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

packages/pdf-handler/package.json

@@ -27,7 +27,7 @@
   },
   "dependencies": {
     "@google-cloud/functions-framework": "3.1.2",
-    "@google-cloud/pubsub": "^2.16.3",
+    "@google-cloud/pubsub": "^3.4.1",
     "@google-cloud/storage": "^5.18.1",
     "axios": "^0.27.2",
     "concurrently": "^7.0.0",