⬆️ Update dependency style-loader to v4

Author: renovate[bot]

package.json

@@ -57,7 +57,7 @@
     "react-hot-loader": "^3.1.3",
     "redux-immutable-state-invariant": "^2.1.0",
     "sass-loader": "^6.0.6",
-    "style-loader": "^0.20.2",
+    "style-loader": "^4.0.0",
     "url-loader": "^0.6.2",
     "webpack": "^3.11.0",
     "webpack-dev-middleware": "^2.0.6",