Build(deps-dev): bump stylus-loader from 7.1.3 to 8.1.0

Bumps [stylus-loader](https://github.com/webpack-contrib/stylus-loader) from 7.1.3 to 8.1.0.
- [Release notes](https://github.com/webpack-contrib/stylus-loader/releases)
- [Changelog](https://github.com/webpack-contrib/stylus-loader/blob/master/CHANGELOG.md)
- [Commits](webpack-contrib/stylus-loader@v7.1.3...v8.1.0)

---
updated-dependencies:
- dependency-name: stylus-loader
  dependency-type: direct:development
  update-type: version-update:semver-major
...

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