Update dependency node-sass to v4.9.4

Author: renovate-bot

package.json

@@ -58,7 +58,7 @@
     "jest": "23.6.0",
     "jsdom": "12.2.0",
     "lint-staged": "7.3.0",
-    "node-sass": "4.9.3",
+    "node-sass": "4.9.4",
     "prettier": "1.14.3",
     "react": "16.5.2",
     "react-dom": "16.5.2",