chore(package): update nyc to version 12.0.2

Closes #49

Author: greenkeeper[bot]

package.json

@@ -89,7 +89,7 @@
     "conventional-changelog-cli": "^1.3.13",
     "cross-env": "^5.1.3",
     "docsify-cli": "^4.2.0",
-    "nyc": "^11.4.1",
+    "nyc": "^12.0.2",
     "ts-node": "^5.0.0",
     "typescript": "^2.7.2"
   }