chore(deps): bump @google-cloud/pubsub from 2.18.4 to 2.19.4

Bumps [@google-cloud/pubsub](https://github.com/googleapis/nodejs-pubsub) from 2.18.4 to 2.19.4.
- [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/v2.18.4...v2.19.4)

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

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

packages/fxa-customs-server/package.json

@@ -23,7 +23,7 @@
     "format": "prettier --write --config ../../_dev/.prettierrc '**'"
   },
   "dependencies": {
-    "@google-cloud/pubsub": "^2.18.4",
+    "@google-cloud/pubsub": "^2.19.4",
     "@hapi/hapi": "^20.2.1",
     "@hapi/hoek": "^10.0.0",
     "@sentry/node": "^6.19.1",

packages/fxa-event-broker/package.json

@@ -33,7 +33,7 @@
   "readmeFilename": "README.md",
   "dependencies": {
     "@google-cloud/firestore": "^5.0.2",
-    "@google-cloud/pubsub": "^2.18.4",
+    "@google-cloud/pubsub": "^2.19.4",
     "@grpc/grpc-js": "^1.1.3",
     "@hapi/hoek": "^10.0.0",
     "@nestjs/common": "^8.4.7",