chore(deps): update dependency @google-cloud/nodejs-repo-tools to v3 (#119)

Author: renovate[bot]

cloud-tasks/package.json

@@ -20,7 +20,7 @@
     "yargs": "^12.0.1"
   },
   "devDependencies": {
-    "@google-cloud/nodejs-repo-tools": "^2.3.0",
+    "@google-cloud/nodejs-repo-tools": "^3.0.0",
     "ava": "^0.25.0",
     "proxyquire": "^2.0.1",
     "sinon": "^7.0.0"