Update node-sass to work with newest node version

package.json

@@ -52,7 +52,7 @@
     "file-loader": "^1.1.11",
     "html-webpack-plugin": "^3.2.0",
     "mini-css-extract-plugin": "^0.4.0",
-    "node-sass": "^4.9.0",
+    "node-sass": "^4.12.0",
     "optimize-css-assets-webpack-plugin": "^4.0.2",
     "postcss-loader": "2.0.6",
     "sass-loader": "^7.0.2",