deps: update gax.version to v2.1.0 (#432)

Author: renovate-bot

pom.xml

@@ -56,7 +56,7 @@
     <site.installationModule>${project.artifactId}</site.installationModule>
 
     <grpc.version>1.39.0</grpc.version>
-    <gax.version>2.0.0</gax.version>
+    <gax.version>2.1.0</gax.version>
     <grpc-gcp.version>1.1.0</grpc-gcp.version>
     <guava.version>30.1.1-jre</guava.version>
     <protobuf.version>3.17.3</protobuf.version>