Bump com.google.protobuf:protobuf-java from 3.23.4 to 4.28.3

Bumps [com.google.protobuf:protobuf-java](https://github.com/protocolbuffers/protobuf) from 3.23.4 to 4.28.3.
- [Release notes](https://github.com/protocolbuffers/protobuf/releases)
- [Changelog](https://github.com/protocolbuffers/protobuf/blob/main/protobuf_release.bzl)
- [Commits](https://github.com/protocolbuffers/protobuf/commits)

---
updated-dependencies:
- dependency-name: com.google.protobuf:protobuf-java
  dependency-type: direct:production
  update-type: version-update:semver-major
...

Signed-off-by: dependabot[bot] <support@github.com>

Author: dependabot[bot]

demo/demo-etcd/consumer/pom.xml

@@ -37,7 +37,7 @@
     <dependency>
       <groupId>com.google.protobuf</groupId>
       <artifactId>protobuf-java</artifactId>
-      <version>3.25.5</version>
+      <version>4.28.3</version>
       <scope>runtime</scope>
     </dependency>
     <dependency>

demo/demo-etcd/gateway/pom.xml

@@ -41,7 +41,7 @@
     <dependency>
       <groupId>com.google.protobuf</groupId>
       <artifactId>protobuf-java</artifactId>
-      <version>3.25.3</version>
+      <version>4.28.3</version>
       <scope>runtime</scope>
     </dependency>
     <dependency>

demo/demo-etcd/provider/pom.xml

@@ -41,7 +41,7 @@
     <dependency>
       <groupId>com.google.protobuf</groupId>
       <artifactId>protobuf-java</artifactId>
-      <version>3.25.3</version>
+      <version>4.28.3</version>
       <scope>runtime</scope>
     </dependency>
     <dependency>

dependencies/default/pom.xml

@@ -74,7 +74,7 @@
     <netty.version>4.1.113.Final</netty.version>
     <okhttp3.version>4.12.0</okhttp3.version>
     <prometheus.version>0.16.0</prometheus.version>
-    <protobuf.version>3.23.4</protobuf.version>
+    <protobuf.version>4.28.3</protobuf.version>
     <protostuff.version>1.8.0</protostuff.version>
     <protostuff-parser.version>2.2.27</protostuff-parser.version>
     <reactive-streams.version>1.0.4</reactive-streams.version>