chore(package): update nyc to version 12.0.2 (#40)

Closes #39

Author: gucong3000

package.json

@@ -19,7 +19,7 @@
     "eslint-plugin-promise": "^3.7.0",
     "eslint-plugin-standard": "^3.1.0",
     "mocha": "^5.1.1",
-    "nyc": "^11.7.1"
+    "nyc": "^12.0.2"
   },
   "homepage": "https://github.com/gucong3000/mirror-config-china#readme",
   "keywords": [