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

Closes #39

Author: greenkeeper[bot]

package.json

@@ -64,7 +64,7 @@
     "jest-styled-components": "^6.2.1",
     "jsdoc": "^3.5.5",
     "minami": "^1.2.3",
-    "mini-css-extract-plugin": "^0.7.0",
+    "mini-css-extract-plugin": "^0.9.0",
     "react": "^16.5.2",
     "react-dom": "^16.5.2",
     "rimraf": "^2.6.2",