Bump nanoid and mocha in /react-express-mysql/backend

Removes [nanoid](https://github.com/ai/nanoid). It's no longer used after updating ancestor dependency [mocha](https://github.com/mochajs/mocha). These dependencies need to be updated together.


Removes `nanoid`

Updates `mocha` from 9.2.2 to 12.0.3
- [Release notes](https://github.com/mochajs/mocha/releases)
- [Changelog](https://github.com/mochajs/mocha/blob/main/CHANGELOG.md)
- [Commits](https://github.com/mochajs/mocha/compare/v9.2.2...v12.0.3)

---
updated-dependencies:
- dependency-name: nanoid
  dependency-version:
  dependency-type: indirect
- dependency-name: mocha
  dependency-version: 12.0.3
  dependency-type: direct:development
...

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

react-express-mysql/backend/package.json

@@ -23,7 +23,7 @@
     "chai": "^4.2.0",
     "chai-http": "^4.3.0",
     "cross-env": "^7.0.2",
-    "mocha": "^9.2.2",
+    "mocha": "^12.0.3",
     "nodemon": "^2.0.4"
   }
 }