Bump serve-static and express in /ui (#2728)

Bumps [serve-static](https://github.com/expressjs/serve-static) to 1.16.2 and updates ancestor dependency [express](https://github.com/expressjs/express). These dependencies need to be updated together.


Updates `serve-static` from 1.15.0 to 1.16.2
- [Release notes](https://github.com/expressjs/serve-static/releases)
- [Changelog](https://github.com/expressjs/serve-static/blob/v1.16.2/HISTORY.md)
- [Commits](expressjs/serve-static@v1.15.0...v1.16.2)

Updates `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: serve-static
  dependency-type: indirect
- dependency-name: express
  dependency-type: direct:production
...

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

ui/package.json

@@ -69,7 +69,7 @@
         "denali-css": "2.5.1",
         "downshift": "6.1.9",
         "emotion": "11.0.0",
-        "express": "4.19.2",
+        "express": "4.21.0",
         "fetchr": "0.5.45",
         "flatpickr": "4.6.13",
         "helmet": "6.0.0",