fix(deps): update protobuf monorepo to v4 (GoogleCloudPlatform#2882)

Author: renovate-bot

src/adservice/build.gradle

@@ -17,7 +17,7 @@ version = "0.1.0-SNAPSHOT"
 def grpcVersion = "1.69.1"
 def jacksonCoreVersion = "2.18.2"
 def jacksonDatabindVersion = "2.18.2"
-def protocVersion = "3.25.5"
+def protocVersion = "4.29.3"
 
 tasks.withType(JavaCompile) {
     sourceCompatibility = JavaVersion.VERSION_19