Bump express from 4.20.0 to 4.21.0 (#764)

Bumps [express](https://github.com/expressjs/express) from 4.20.0 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@4.20.0...4.21.0)

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

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

package.json

@@ -48,7 +48,7 @@
     "dotenv-expand": "^5.1.0",
     "eslint": "^8.57.1",
     "eslint-webpack-plugin": "^4.2.0",
-    "express": "^4.20.0",
+    "express": "^4.21.0",
     "file-loader": "^6.2.0",
     "fs-extra": "^11.2.0",
     "html-webpack-plugin": "^5.5.0",