Update dependency css-loader to v4.2.1

[renovate[bot]]

This PR contains the following updates:

Package	Type	Update	Change
css-loader	devDependencies	patch	4.2.0 -> 4.2.1

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Release Notes

webpack-contrib/css-loader

### [`v4.2.1`](https://togithub.com/webpack-contrib/css-loader/blob/master/CHANGELOG.md#​421-httpsgithubcomwebpack-contribcss-loadercomparev420v421-2020-08-06) [Compare Source](https://togithub.com/webpack-contrib/css-loader/compare/v4.2.0...v4.2.1)

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