Bump css-loader from 3.2.1 to 5.2.6

Bumps [css-loader](https://github.com/webpack-contrib/css-loader) from 3.2.1 to 5.2.6.
- [Release notes](https://github.com/webpack-contrib/css-loader/releases)
- [Changelog](https://github.com/webpack-contrib/css-loader/blob/master/CHANGELOG.md)
- [Commits](webpack/css-loader@v3.2.1...v5.2.6)

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

Author: dependabot[bot]