chore(package): update nyc to version 12.0.1

Author: greenkeeper[bot]

package.json

@@ -91,7 +91,7 @@
     "karma-sourcemap-writer": "^0.1.2",
     "karma-webpack": "^3.0.0",
     "mocha": "^5.2.0",
-    "nyc": "^11.8.0",
+    "nyc": "^12.0.1",
     "prettier": "^1.12.1",
     "publish-please": "^2.4.1",
     "reflect-metadata": "^0.1.12",