fix(deps): update dependency google-auth-library to v4 (#493)

renovate[bot] · Benjamin E. Coe · commit 03236f41007b · 2019-05-09T08:58:48.000-07:00
diff --git a/package.json b/package.json
@@ -12,7 +12,7 @@
     "@grpc/grpc-js": "^0.4.0",
     "@grpc/proto-loader": "^0.5.0",
     "duplexify": "^3.6.0",
-    "google-auth-library": "^3.0.0",
+    "google-auth-library": "^4.0.0",
     "is-stream-ended": "^0.1.4",
     "lodash.at": "^4.6.0",
     "lodash.has": "^4.5.2",
