build(deps): bump nanoid and mocha in /backend

Bumps [nanoid](https://github.com/ai/nanoid) to 3.3.1 and updates ancestor dependency [mocha](https://github.com/mochajs/mocha). These dependencies need to be updated together.


Updates `nanoid` from 3.1.25 to 3.3.1
- [Release notes](https://github.com/ai/nanoid/releases)
- [Changelog](https://github.com/ai/nanoid/blob/main/CHANGELOG.md)
- [Commits](ai/nanoid@3.1.25...3.3.1)

Updates `mocha` from 9.1.3 to 9.2.2
- [Release notes](https://github.com/mochajs/mocha/releases)
- [Changelog](https://github.com/mochajs/mocha/blob/master/CHANGELOG.md)
- [Commits](mochajs/mocha@v9.1.3...v9.2.2)

---
updated-dependencies:
- dependency-name: nanoid
  dependency-type: indirect
- dependency-name: mocha
  dependency-type: direct:development
...

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

Author: dependabot[bot]

backend/package-lock.json

@@ -38,7 +38,7 @@
     "chai-as-promised": "^7.1.1",
     "eslint": "^8.5.0",
     "jsonwebtoken": "^8.5.1",
-    "mocha": "^9.1.3",
+    "mocha": "^9.2.2",
     "nodemon": "^2.0.20",
     "nyc": "^15.1.0",
     "supertest": "^3.4.2"