chore(deps): bump validator from 13.15.0 to 13.15.23 in /backend

Bumps [validator](https://github.com/validatorjs/validator.js) from 13.15.0 to 13.15.23.
- [Release notes](https://github.com/validatorjs/validator.js/releases)
- [Changelog](https://github.com/validatorjs/validator.js/blob/master/CHANGELOG.md)
- [Commits](validatorjs/validator.js@13.15.0...13.15.23)

---
updated-dependencies:
- dependency-name: validator
  dependency-version: 13.15.23
  dependency-type: direct:production
...

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

Author: dependabot[bot]

backend/package-lock.json

@@ -31,7 +31,7 @@
     "octokit": "^4.1.2",
     "smee-client": "^3.1.1",
     "update-dotenv": "^1.1.1",
-    "validator": "^13.15.0",
+    "validator": "^13.15.23",
     "why-is-node-running": "^3.2.2"
   },
   "devDependencies": {