Bump express from 4.19.2 to 4.21.0 in /graph-sample

Bumps [express](https://github.com/expressjs/express) from 4.19.2 to 4.21.0.
- [Release notes](https://github.com/expressjs/express/releases)
- [Changelog](https://github.com/expressjs/express/blob/4.21.0/History.md)
- [Commits](expressjs/express@4.19.2...4.21.0)

---
updated-dependencies:
- dependency-name: express
  dependency-type: direct:production
  update-type: version-update:semver-minor
...

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

Author: dependabot[bot]

graph-sample/package-lock.json

@@ -16,7 +16,7 @@
     "date-fns-tz": "^2.0.1",
     "debug": "^4.3.7",
     "dotenv": "^16.4.5",
-    "express": "^4.19.2",
+    "express": "^4.21.0",
     "express-promise-router": "^4.1.1",
     "express-session": "^1.18.0",
     "express-validator": "^7.2.0",