Update css-loader requirement from ^2.1.1 to ^3.1.0

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/compare/v2.1.1...v3.1.0)

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

package.json

@@ -11,7 +11,7 @@
   "devDependencies": {
     "bourbon": "~4.3",
     "bourbon-neat": "~4.0",
-    "css-loader": "^2.1.1",
+    "css-loader": "^3.1.0",
     "file-loader": "^3.0.1",
     "font-awesome": "^4.7.0",
     "imports-loader": "^0.8.0",