Bump path-to-regexp, serve-handler and express in /docusaurus

Bumps [path-to-regexp](https://github.com/pillarjs/path-to-regexp), [serve-handler](https://github.com/vercel/serve-handler) and [express](https://github.com/expressjs/express). These dependencies needed to be updated together.

Updates `path-to-regexp` from 0.1.10 to 1.9.0
- [Release notes](https://github.com/pillarjs/path-to-regexp/releases)
- [Changelog](https://github.com/pillarjs/path-to-regexp/blob/master/History.md)
- [Commits](pillarjs/path-to-regexp@v0.1.10...v1.9.0)

Updates `serve-handler` from 6.1.5 to 6.1.6
- [Release notes](https://github.com/vercel/serve-handler/releases)
- [Commits](vercel/serve-handler@6.1.5...6.1.6)

Updates `express` from 4.21.1 to 4.21.2
- [Release notes](https://github.com/expressjs/express/releases)
- [Changelog](https://github.com/expressjs/express/blob/4.21.2/History.md)
- [Commits](expressjs/express@4.21.1...4.21.2)

---
updated-dependencies:
- dependency-name: path-to-regexp
  dependency-type: indirect
- dependency-name: serve-handler
  dependency-type: indirect
- dependency-name: express
  dependency-type: indirect
...

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