Bump express from 4.18.3 to 4.19.2 in /backend

Bumps [express](https://github.com/expressjs/express) from 4.18.3 to 4.19.2.
- [Release notes](https://github.com/expressjs/express/releases)
- [Changelog](https://github.com/expressjs/express/blob/master/History.md)
- [Commits](expressjs/express@4.18.3...4.19.2)

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

Signed-off-by: dependabot[bot] <[email protected]>

Author: dependabot[bot]

backend/package-lock.json

@@ -26,7 +26,7 @@
     "bcryptjs": "^2.4.3",
     "cors": "^2.8.5",
     "dotenv": "^16.4.5",
-    "express": "^4.18.3",
+    "express": "^4.19.2",
     "jsonwebtoken": "^9.0.2",
     "mongoose": "^8.2.0",
     "morgan": "^1.10.0"