deps: grpc v1.71.0

https://github.com/grpc/grpc-java/releases/tag/v1.71.0 is the latest in the gRPC.

Author: suztomo

gapic-generator-java-pom-parent/pom.xml

@@ -26,7 +26,7 @@
     <!-- External dependencies, especially gRPC and Protobuf version, should be
         consistent across modules in this repository -->
     <javax.annotation-api.version>1.3.2</javax.annotation-api.version>
-    <grpc.version>1.70.0</grpc.version>
+    <grpc.version>1.71.0</grpc.version>
     <google.auth.version>1.33.1</google.auth.version>
     <google.http-client.version>1.46.3</google.http-client.version>
     <gson.version>2.12.1</gson.version>