Bump express from 4.18.2 to 4.20.0 in /packages/backend

Bumps [express](https://github.com/expressjs/express) from 4.18.2 to 4.20.0.
- [Release notes](https://github.com/expressjs/express/releases)
- [Changelog](https://github.com/expressjs/express/blob/master/History.md)
- [Commits](expressjs/express@4.18.2...4.20.0)

---
updated-dependencies:
- dependency-name: express
  dependency-type: direct:production
...

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

packages/backend/package.json

@@ -35,7 +35,7 @@
     "app": "link:../app",
     "better-sqlite3": "9.4.0",
     "dockerode": "3.3.5",
-    "express": "4.18.2",
+    "express": "4.20.0",
     "express-promise-router": "4.1.1",
     "knex": "2.5.1",
     "luxon": "3.2.1",