Bump debug from 2.6.9 to 3.1.0 in /examples/express-demo (#351)

Bumps [debug](https://github.com/debug-js/debug) from 2.6.9 to 3.1.0.
- [Release notes](https://github.com/debug-js/debug/releases)
- [Changelog](https://github.com/debug-js/debug/blob/3.1.0/CHANGELOG.md)
- [Commits](debug-js/debug@2.6.9...3.1.0)

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

Signed-off-by: dependabot[bot] <[email protected]>

Signed-off-by: dependabot[bot] <[email protected]>
Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>

Author: dependabot[bot]

examples/express-demo/package-lock.json

@@ -16,7 +16,7 @@
   "author": "Sandrino Di Mattia",
   "license": "MIT",
   "dependencies": {
-    "debug": "^2.6.9",
+    "debug": "^3.1.0",
     "express": "^4.17.0",
     "express-jwt": "^8.3.0"
   }