fix(deps): update dependency google-gax to ^0.25.0 (#456)

Author: renovate[bot]

handwritten/pubsub/package.json

@@ -57,7 +57,7 @@
     "duplexify": "^3.5.4",
     "extend": "^3.0.1",
     "google-auth-library": "^3.0.0",
-    "google-gax": "^0.24.0",
+    "google-gax": "^0.25.0",
     "is": "^3.0.1",
     "is-stream-ended": "^0.1.4",
     "lodash.chunk": "^4.2.0",