fix(deps): update dependency google-gax to ^0.25.0 (#505)

Author: renovate[bot]

package.json

@@ -56,7 +56,7 @@
     "events-intercept": "^2.0.0",
     "extend": "^3.0.1",
     "google-auth-library": "^3.0.0",
-    "google-gax": "^0.24.0",
+    "google-gax": "^0.25.0",
     "is": "^3.2.1",
     "lodash.merge": "^4.6.1",
     "lodash.snakecase": "^4.1.1",