chore(deps): update dependency nyc to v13 (#76)

Author: renovate[bot]

packages/google-cloud-resourcemanager/package.json

@@ -89,7 +89,7 @@
     "jsdoc": "^3.5.5",
     "methmeth": "^1.1.0",
     "mocha": "^5.0.0",
-    "nyc": "^12.0.2",
+    "nyc": "^13.0.0",
     "power-assert": "^1.4.4",
     "prettier": "^1.7.4",
     "proxyquire": "^2.0.0",