Bump vite and vitepress

Bumps [vite](https://github.com/vitejs/vite/tree/HEAD/packages/vite) and [vitepress](https://github.com/vuejs/vitepress). These dependencies needed to be updated together.

Updates `vite` from 5.4.19 to 5.4.20
- [Release notes](https://github.com/vitejs/vite/releases)
- [Changelog](https://github.com/vitejs/vite/blob/v5.4.20/packages/vite/CHANGELOG.md)
- [Commits](https://github.com/vitejs/vite/commits/v5.4.20/packages/vite)

Updates `vitepress` from 1.0.0-rc.45 to 1.6.4
- [Release notes](https://github.com/vuejs/vitepress/releases)
- [Changelog](https://github.com/vuejs/vitepress/blob/v1.6.4/CHANGELOG.md)
- [Commits](vuejs/vitepress@v1.0.0-rc.45...v1.6.4)

---
updated-dependencies:
- dependency-name: vite
  dependency-version: 5.4.20
  dependency-type: direct:development
- dependency-name: vitepress
  dependency-version: 1.6.4
  dependency-type: direct:development
...

Signed-off-by: dependabot[bot] <support@github.com>

Author: dependabot[bot]