chore(package): update mini-css-extract-plugin to version 0.9.0

Author: greenkeeper[bot]

package.json

@@ -31,7 +31,7 @@
     "cross-env": "6.0.3",
     "css-loader": "3.4.0",
     "file-loader": "5.0.2",
-    "mini-css-extract-plugin": "0.8.2",
+    "mini-css-extract-plugin": "0.9.0",
     "postcss-loader": "3.0.0",
     "sass": "1.23.7",
     "sass-loader": "8.0.0",