fix(deps): update dependency google-auth-library to v4 (#475)

Author: renovate[bot]

package.json

@@ -57,7 +57,7 @@
     "dot-prop": "^5.0.0",
     "escape-string-regexp": "^2.0.0",
     "extend": "^3.0.0",
-    "google-auth-library": "^3.0.0",
+    "google-auth-library": "^4.0.0",
     "google-gax": "^0.26.0",
     "is": "^3.0.1",
     "is-utf8": "^0.2.1",