Update fs-extra to the latest version 🚀 (#175)

* chore(package): update fs-extra to version 8.0.0

* chore(package): update lockfile package-lock.json

Author: greenkeeper[bot]

package-lock.json

@@ -38,7 +38,7 @@
   "devDependencies": {
     "ava": "^1.4.1",
     "dir-compare": "^1.7.2",
-    "fs-extra": "^7.0.1",
+    "fs-extra": "^8.0.0",
     "html-webpack-plugin": "^3.2.0",
     "nyc": "^14.0.0",
     "webpack": "^4.30.0",