build: bump express from 4.18.2 to 4.21.2 in /App/frontend-app

Bumps [express](https://github.com/expressjs/express) from 4.18.2 to 4.21.2.
- [Release notes](https://github.com/expressjs/express/releases)
- [Changelog](https://github.com/expressjs/express/blob/4.21.2/History.md)
- [Commits](expressjs/express@4.18.2...4.21.2)

---
updated-dependencies:
- dependency-name: express
  dependency-type: direct:development
  update-type: version-update:semver-minor
...

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

Author: dependabot[bot]

App/frontend-app/package-lock.json

@@ -74,7 +74,7 @@
         "eslint-plugin-react": "^7.37.4",
         "eslint-plugin-react-hooks": "^5.1.0",
         "eslint-plugin-react-refresh": "^0.4.16",
-        "express": "^4.18.2",
+        "express": "^4.21.2",
         "jest": "^29.7.0",
         "jest-environment-jsdom": "^29.7.0",
         "nodemon": "^3.1.9",