Update Dataflow Dependency Java (apache#38542)

Author: tarun-google

buildSrc/src/main/groovy/org/apache/beam/gradle/BeamModulePlugin.groovy

@@ -743,7 +743,7 @@ class BeamModulePlugin implements Plugin<Project> {
         google_api_common                           : "com.google.api:api-common", // google_cloud_platform_libraries_bom sets version
         google_api_services_bigquery                : "com.google.apis:google-api-services-bigquery:v2-rev20251012-2.0.0",  // [bomupgrader] sets version
         google_api_services_cloudresourcemanager    : "com.google.apis:google-api-services-cloudresourcemanager:v1-rev20250606-2.0.0",  // [bomupgrader] sets version
-        google_api_services_dataflow                : "com.google.apis:google-api-services-dataflow:v1b3-rev20260405-$google_clients_version",
+        google_api_services_dataflow                : "com.google.apis:google-api-services-dataflow:v1b3-rev20260503-$google_clients_version",
         google_api_services_healthcare              : "com.google.apis:google-api-services-healthcare:v1-rev20240130-$google_clients_version",
         google_api_services_pubsub                  : "com.google.apis:google-api-services-pubsub:v1-rev20220904-$google_clients_version",
         google_api_services_storage                 : "com.google.apis:google-api-services-storage:v1-rev20260204-2.0.0",  // [bomupgrader] sets version