Bump express from 4.18.2 to 4.19.2 in /backend

Bumps [express](https://github.com/expressjs/express) from 4.18.2 to 4.19.2.
- [Release notes](https://github.com/expressjs/express/releases)
- [Changelog](https://github.com/expressjs/express/blob/master/History.md)
- [Commits](https://github.com/expressjs/express/compare/4.18.2...4.19.2)

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

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

backend/package.json

@@ -34,7 +34,7 @@
     "compression": "^1.7.4",
     "config": "^3.2.3",
     "execa": "^5.1.1",
-    "express": "^4.18.2",
+    "express": "^4.19.2",
     "express-session": "^1.17.3",
     "feed": "^4.2.2",
     "fluent-ffmpeg": "^2.1.2",