Update pom.xml

Author: blakeli0

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

@@ -31,7 +31,7 @@
     <google.http-client.version>1.47.1</google.http-client.version>
     <gson.version>2.12.1</gson.version>
     <guava.version>33.4.0-jre</guava.version>
-    <protobuf.version>3.25.8</protobuf.version>
+    <protobuf.version>4.32.1</protobuf.version>
     <opentelemetry.version>1.47.0</opentelemetry.version>
     <maven.compiler.release>8</maven.compiler.release>
     <errorprone.version>2.38.0</errorprone.version>