chore(package): update nyc to version 12.0.2

Closes #6

Author: greenkeeper[bot]

package.json

@@ -25,7 +25,7 @@
     "eslint": "^4.8.0",
     "eslint-config-google": "^0.9.1",
     "mocha": "^4.0.1",
-    "nyc": "^11.2.1"
+    "nyc": "^12.0.2"
   },
   "dependencies": {
     "fs-extra": "^4.0.2",