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

Closes #64

Author: greenkeeper[bot]

package.json

@@ -61,7 +61,7 @@
     "async": "^2.1.4",
     "ci-publish": "^1.3.0",
     "download-manager": "^0.1.3",
-    "fs-extra": "^5.0.0",
+    "fs-extra": "^8.0.0",
     "nodeos-linux": "^4.15.10",
     "prebuild": "^7.4.0"
   },