Bump protobuf-java from 3.6.1 to 3.16.1 in /kafka-webview-ui

Bumps [protobuf-java](https://github.com/protocolbuffers/protobuf) from 3.6.1 to 3.16.1.
- [Release notes](https://github.com/protocolbuffers/protobuf/releases)
- [Changelog](https://github.com/protocolbuffers/protobuf/blob/master/generate_changelog.py)
- [Commits](protocolbuffers/protobuf@v3.6.1...v3.16.1)

---
updated-dependencies:
- dependency-name: com.google.protobuf:protobuf-java
  dependency-type: direct:production
...

Signed-off-by: dependabot[bot] <[email protected]>

Author: dependabot[bot]

kafka-webview-ui/pom.xml

@@ -35,7 +35,7 @@
         <avro.version>1.11.0</avro.version>
         <bootstrap.version>4.0.0-beta</bootstrap.version>
         <kafka.version>2.8.1</kafka.version>
-        <protobuf.version>3.6.1</protobuf.version>
+        <protobuf.version>3.16.1</protobuf.version>
         <thymeleaf.version>3.0.14.RELEASE</thymeleaf.version>
         <guava.version>31.0.1-jre</guava.version>
     </properties>