chore(package): update nyc to version 12.0.2

Closes #36

Author: greenkeeper[bot]

package.json

@@ -10,7 +10,7 @@
   "devDependencies": {
     "ava": "^0.21.0",
     "coveralls": "2.x",
-    "nyc": "^11.0.3",
+    "nyc": "^12.0.2",
     "standard": "^10.0.2",
     "webpack": "^3.0.0"
   },