chore(deps): update dependency google-gax to v3 (GoogleCloudPlatform#149)

Co-authored-by: Alexander Fenster <fenster@google.com>

Author: renovate-bot

package.json

@@ -39,7 +39,7 @@
     "@google-cloud/spanner": "^6.0.0",
     "c8": "^7.7.2",
     "google-auth-library": "^8.0.0",
-    "google-gax": "^2.14.1",
+    "google-gax": "^3.0.0",
     "google-protobuf": "^3.17.1",
     "grpc": "^1.24.10",
     "grpc-tools": "^1.11.1",