build(deps): bump vitepress from 1.0.0-rc.9 to 1.0.0-rc.15

Bumps [vitepress](https://github.com/vuejs/vitepress) from 1.0.0-rc.9 to 1.0.0-rc.15.
- [Release notes](https://github.com/vuejs/vitepress/releases)
- [Changelog](https://github.com/vuejs/vitepress/blob/main/CHANGELOG.md)
- [Commits](vuejs/vitepress@v1.0.0-rc.9...v1.0.0-rc.15)

---
updated-dependencies:
- dependency-name: vitepress
  dependency-type: direct:production
  update-type: version-update:semver-patch
...

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