Bump vite from 5.4.19 to 5.4.21 in /examples/vitepress

Bumps [vite](https://github.com/vitejs/vite/tree/HEAD/packages/vite) from 5.4.19 to 5.4.21.
- [Release notes](https://github.com/vitejs/vite/releases)
- [Changelog](https://github.com/vitejs/vite/blob/v5.4.21/packages/vite/CHANGELOG.md)
- [Commits](https://github.com/vitejs/vite/commits/v5.4.21/packages/vite)

---
updated-dependencies:
- dependency-name: vite
  dependency-version: 5.4.21
  dependency-type: indirect
...

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

Author: dependabot[bot]