chore(package): update mini-css-extract-plugin to version 0.8.0

Author: greenkeeper[bot]

package.json

@@ -26,7 +26,7 @@
     "coveralls": "^3.0.3",
     "css-loader": "^3.0.0",
     "jest": "^24.8.0",
-    "mini-css-extract-plugin": "^0.7.0",
+    "mini-css-extract-plugin": "^0.8.0",
     "webpack": "^4.31.0",
     "webpack-cli": "^3.3.2"
   }