Bump @vuepress/bundler-webpack from 2.0.0-rc.14 to 2.0.0-rc.15

Bumps [@vuepress/bundler-webpack](https://github.com/vuepress/core) from 2.0.0-rc.14 to 2.0.0-rc.15.
- [Release notes](https://github.com/vuepress/core/releases)
- [Changelog](https://github.com/vuepress/core/blob/main/CHANGELOG.md)
- [Commits](vuepress/core@v2.0.0-rc.14...v2.0.0-rc.15)

---
updated-dependencies:
- dependency-name: "@vuepress/bundler-webpack"
  dependency-type: direct:development
  update-type: version-update:semver-patch
...

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