chore(package): update nyc to version 8.3.1

https://greenkeeper.io/

Author: greenkeeperio-bot

package.json

@@ -70,7 +70,7 @@
     "eslint-plugin-xo": "^1.0.0",
     "husky": "^0.11.5",
     "np": "^2.8.0",
-    "nyc": "^8.1.0",
+    "nyc": "^8.3.1",
     "updtr": "^0.2.1"
   },
   "ava": {