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-contrib/css-loader@v3.6.0...v4.0.0)

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

package.json

@@ -35,7 +35,7 @@
     "babel-eslint": "^10.1.0",
     "babel-loader": "^8.1.0",
     "babel-preset-stage-2": "^6.24.1",
-    "css-loader": "^3.6.0",
+    "css-loader": "^4.0.0",
     "eslint": "^7.5.0",
     "react": "^16.13.1",
     "react-dom": "^16.13.1",