Bump protobuf-java in /tensorflow/java/maven/tensorflow-hadoop

Bumps [protobuf-java](https://github.com/protocolbuffers/protobuf) from 3.5.1 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@v3.5.1...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]

tensorflow/java/maven/tensorflow-hadoop/pom.xml

@@ -15,7 +15,7 @@
         <maven.compiler.source>1.6</maven.compiler.source>
         <maven.compiler.target>1.6</maven.compiler.target>
         <hadoop.version>2.6.0</hadoop.version>
-        <protobuf.version>3.5.1</protobuf.version>
+        <protobuf.version>3.16.1</protobuf.version>
         <junit.version>4.13.1</junit.version>
     </properties>