fix(package): update fs-extra to version 6.0.0

Author: greenkeeper[bot]

package.json

@@ -18,7 +18,7 @@
   "dependencies": {
     "@semantic-release/error": "^2.1.0",
     "aggregate-error": "^1.0.0",
-    "fs-extra": "^5.0.0",
+    "fs-extra": "^6.0.0",
     "lodash": "^4.17.4"
   },
   "devDependencies": {