Bump express from 4.17.1 to 4.17.3 in /backend

Bumps [express](https://github.com/expressjs/express) from 4.17.1 to 4.17.3.
- [Release notes](https://github.com/expressjs/express/releases)
- [Changelog](https://github.com/expressjs/express/blob/master/History.md)
- [Commits](expressjs/express@4.17.1...4.17.3)

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

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

Author: dependabot[bot]

backend/package.json

@@ -11,7 +11,7 @@
 		"body-parser": "^1.19.0",
 		"compression": "^1.7.4",
 		"config": "^3.3.1",
-		"express": "^4.17.1",
+		"express": "^4.17.3",
 		"express-fileupload": "^1.1.9",
 		"gravatar": "^1.8.0",
 		"json-schema-ref-parser": "^8.0.0",