Bump css-loader from 3.6.0 to 4.0.0

Bumps [css-loader](https://github.com/webpack-contrib/css-loader) from 3.6.0 to 4.0.0.
- [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@v3.6.0...v4.0.0)

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

Author: dependabot[bot]

package.json

@@ -29,7 +29,7 @@
     "clean-webpack-plugin": "3.0.0",
     "copy-webpack-plugin": "6.0.3",
     "cross-env": "7.0.2",
-    "css-loader": "3.6.0",
+    "css-loader": "4.0.0",
     "file-loader": "6.0.0",
     "mini-css-extract-plugin": "0.9.0",
     "postcss-loader": "3.0.0",