chore(package): update nyc to version 12.0.1

Closes #25

Author: greenkeeper[bot]

package.json

@@ -69,7 +69,7 @@
     "koaton-exporter": "^1.2.1",
     "mocha": "^4.0.1",
     "npm-run-all": "^4.1.1",
-    "nyc": "11.4.1",
+    "nyc": "12.0.1",
     "ps-tree": "^1.1.0"
   },
   "bin": {