build(deps): bump netty-codec in /java-client

Bumps [netty-codec](https://github.com/netty/netty) from 4.1.42.Final to 4.1.68.Final.
- [Release notes](https://github.com/netty/netty/releases)
- [Commits](netty/netty@netty-4.1.42.Final...netty-4.1.68.Final)

---
updated-dependencies:
- dependency-name: io.netty:netty-codec
  dependency-type: direct:production
...

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

java-client/pom.xml

@@ -60,7 +60,7 @@
     <apache.commons.lang3.version>3.1</apache.commons.lang3.version>
     <zkclient.version>0.2</zkclient.version>
     <json.version>20160810</json.version>
-    <netty.version>4.1.42.Final</netty.version>
+    <netty.version>4.1.68.Final</netty.version>
     <zstd-jni.version>1.3.7-1</zstd-jni.version>
     <libthrift.version>0.11.0</libthrift.version>
     <javax.annotation-api.version>1.3.2</javax.annotation-api.version>