fix(package): update fs-extra to version 7.0.0

Author: greenkeeper[bot]

package.json

@@ -21,7 +21,7 @@
  "detect-indent": "^5.0.0",
  "detect-newline": "^2.1.0",
  "execa": "^0.10.0",
- "fs-extra": "^6.0.0",
+ "fs-extra": "^7.0.0",
  "lodash": "^4.17.4",
  "nerf-dart": "^1.0.0",
  "normalize-url": "^3.0.0",