Bump express from 4.21.2 to 5.1.0 in /webserver

Bumps [express](https://github.com/expressjs/express) from 4.21.2 to 5.1.0.
- [Release notes](https://github.com/expressjs/express/releases)
- [Changelog](https://github.com/expressjs/express/blob/master/History.md)
- [Commits](expressjs/express@4.21.2...v5.1.0)

---
updated-dependencies:
- dependency-name: express
  dependency-version: 5.1.0
  dependency-type: direct:production
  update-type: version-update:semver-major
...

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

Author: dependabot[bot]

webserver/package.json

@@ -36,7 +36,7 @@
     "astro": "^4.16.18",
     "debug": "^4.4.0",
     "dset": "^3.1.4",
-    "express": "^4.21.2",
+    "express": "^5.1.0",
     "google-auth-library": "^9.15.1",
     "lit": "^3.3.0",
     "mdast-util-find-and-replace": "^3.0.2",