Bump protobuf.version from 3.19.6 to 4.28.2

Bumps `protobuf.version` from 3.19.6 to 4.28.2.

Updates `com.google.protobuf:protobuf-java` from 3.19.6 to 4.28.2
- [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)

Updates `com.google.protobuf:protobuf-java-util` from 3.19.6 to 4.28.2

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

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

examples/serdes-with-references/pom.xml

@@ -12,7 +12,7 @@
 
   <properties>
     <projectRoot>${project.basedir}/../..</projectRoot>
-    <protobuf.version>3.25.5</protobuf.version>
+    <protobuf.version>4.28.2</protobuf.version>
     <proto-plugin.version>0.6.1</proto-plugin.version>
     <protobuf.googleapi.types.version>2.44.0</protobuf.googleapi.types.version>
   </properties>

pom.xml

@@ -156,7 +156,7 @@
     <okio.version>3.9.1</okio.version>
     <okio-fake-file-system.version>3.9.0</okio-fake-file-system.version>
     <icu4j.version>75.1</icu4j.version>
-    <protobuf.version>3.25.5</protobuf.version>
+    <protobuf.version>4.28.2</protobuf.version>
     <xmlsec.version>4.0.2</xmlsec.version>
     <protobuf.googleapi.types.version>2.44.0</protobuf.googleapi.types.version>
     <wsdl4j.version>1.6.3</wsdl4j.version>