Bump css-loader from 3.6.0 to 4.2.1

Bumps [css-loader](https://github.com/webpack-contrib/css-loader) from 3.6.0 to 4.2.1.
- [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@v3.6.0...v4.2.1)

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

package.json

@@ -98,7 +98,7 @@
     "babel-loader": "^8.1.0",
     "babel-loader-exclude-node-modules-except": "^1.0.3",
     "chai": "^4.2.0",
-    "css-loader": "^3.6.0",
+    "css-loader": "^4.2.1",
     "eslint": "^6.8.0",
     "eslint-config-standard": "^14.1.1",
     "eslint-loader": "^4.0.2",