Bump jsonwebtoken from 8.5.1 to 9.0.0 in /backend

Bumps [jsonwebtoken](https://github.com/auth0/node-jsonwebtoken) from 8.5.1 to 9.0.0.
- [Release notes](https://github.com/auth0/node-jsonwebtoken/releases)
- [Changelog](https://github.com/auth0/node-jsonwebtoken/blob/master/CHANGELOG.md)
- [Commits](auth0/node-jsonwebtoken@v8.5.1...v9.0.0)

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

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Author: dependabot[bot]

backend/package.json

@@ -15,7 +15,7 @@
         "cors": "^2.8.5",
         "express": "^4.16.4",
         "express-jwt": "^6.0.0",
-        "jsonwebtoken": "^8.4.0",
+        "jsonwebtoken": "^9.0.0",
         "newsapi": "^2.4.0",
         "requests": "^0.3.0",
         "rootpath": "^0.1.2",