Update css-loader requirement to ^1.0.0 in /{{cookiecutter.app_name}}

Updates the requirements on [css-loader](https://github.com/webpack-contrib/css-loader) to permit the latest version.
- [Release notes](https://github.com/webpack-contrib/css-loader/releases)
- [Changelog](https://github.com/webpack-contrib/css-loader/blob/master/CHANGELOG.md)
- [Commits](https://github.com/webpack-contrib/css-loader/commits/v1.0.0

)

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