Bump css-loader from 0.27.3 to 0.28.11 in /apps/files

Bumps [css-loader](https://github.com/webpack-contrib/css-loader) from 0.27.3 to 0.28.11.
- [Release notes](https://github.com/webpack-contrib/css-loader/releases)
- [Changelog](https://github.com/webpack-contrib/css-loader/blob/master/CHANGELOG.md)
- [Commits](webpack-contrib/css-loader@v0.27.3...v0.28.11)

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