Bump objection from 2.2.2 to 2.2.16 in /backend

Bumps [objection](https://github.com/vincit/objection.js) from 2.2.2 to 2.2.16.
- [Release notes](https://github.com/vincit/objection.js/releases)
- [Commits](https://github.com/vincit/objection.js/commits/2.2.16)

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

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

backend/package.json

@@ -25,7 +25,7 @@
 		"mysql": "^2.18.1",
 		"node-rsa": "^1.0.8",
 		"nodemon": "^2.0.2",
-		"objection": "^2.1.3",
+		"objection": "^2.2.16",
 		"path": "^0.12.7",
 		"pg": "^7.12.1",
 		"restler": "^3.4.0",