chore(deps): update dependency nyc to v14 (#340)

Author: renovate[bot]

package.json

@@ -65,7 +65,7 @@
     "mocha": "5.2.0",
     "mock-git": "1.0.3",
     "mockery": "2.1.0",
-    "nyc": "13.3.0",
+    "nyc": "14.1.0",
     "shelljs": "0.7.8"
   }
 }