Bump sass-loader from 12.4.0 to 12.6.0

Bumps [sass-loader](https://github.com/webpack-contrib/sass-loader) from 12.4.0 to 12.6.0.
- [Release notes](https://github.com/webpack-contrib/sass-loader/releases)
- [Changelog](https://github.com/webpack-contrib/sass-loader/blob/master/CHANGELOG.md)
- [Commits](https://github.com/webpack-contrib/sass-loader/compare/v12.4.0...v12.6.0

)

---
updated-dependencies:
- dependency-name: sass-loader
  dependency-type: direct:development
  update-type: version-update:semver-minor
...

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