Bump validator from 13.7.0 to 13.15.22 in /react-express-mongodb/backend

Bumps [validator](https://github.com/validatorjs/validator.js) from 13.7.0 to 13.15.22.
- [Release notes](https://github.com/validatorjs/validator.js/releases)
- [Changelog](https://github.com/validatorjs/validator.js/blob/master/CHANGELOG.md)
- [Commits](https://github.com/validatorjs/validator.js/compare/13.7.0...13.15.22)

---
updated-dependencies:
- dependency-name: validator
  dependency-version: 13.15.22
  dependency-type: direct:production
...

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

react-express-mongodb/backend/package.json

@@ -21,7 +21,7 @@
     "mongodb": "^3.0.7",
     "mongoose": "^6.0.9",
     "simple-node-logger": "^18.12.23",
-    "validator": "^13.7.0"
+    "validator": "^13.15.22"
   },
   "devDependencies": {
     "nodemon": "^2.0.3",