fix(deps): update dependency com.google.protobuf:protobuf-java to v4

Author: renovate[bot]

providers/flagd/pom.xml

@@ -36,7 +36,7 @@
         <dependency>
             <groupId>com.google.protobuf</groupId>
             <artifactId>protobuf-java</artifactId>
-            <version>3.25.5</version>
+            <version>4.28.3</version>
         </dependency>
 
         <!-- we inherent dev.openfeature.javasdk and the test dependencies from the parent pom -->