Bump google-auth-library from 10.3.0 to 10.4.0 in /scripts/gcb2slack (#3820)

Bumps [google-auth-library](https://github.com/googleapis/google-auth-library-nodejs) from 10.3.0 to 10.4.0.
- [Release notes](https://github.com/googleapis/google-auth-library-nodejs/releases)
- [Changelog](https://github.com/googleapis/google-auth-library-nodejs/blob/main/CHANGELOG.md)
- [Commits](googleapis/google-auth-library-nodejs@v10.3.0...v10.4.0)

---
updated-dependencies:
- dependency-name: google-auth-library
  dependency-version: 10.4.0
  dependency-type: direct:production
  update-type: version-update:semver-minor
...

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scripts/gcb2slack/package-lock.json

@@ -6,6 +6,6 @@
   "dependencies": {
     "@google-cloud/functions-framework": "^4.0.0",
     "@slack/webhook": "^7.0.6",
-    "google-auth-library": "^10.3.0"
+    "google-auth-library": "^10.4.0"
   }
 }