Bump netty-codec-http from 4.1.48.Final to 4.1.59.Final in /clients

Bumps [netty-codec-http](https://github.com/netty/netty) from 4.1.48.Final to 4.1.59.Final.
- [Release notes](https://github.com/netty/netty/releases)
- [Commits](netty/netty@netty-4.1.48.Final...netty-4.1.59.Final)

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

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

Author: dependabot[bot]

clients/pom.xml

@@ -73,7 +73,7 @@
     <junit.version>4.12</junit.version>
     <lombok.version>1.16.22</lombok.version>
     <mockito.version>2.22.0</mockito.version>
-    <netty.version>4.1.48.Final</netty.version>
+    <netty.version>4.1.59.Final</netty.version>
     <netty-boringssl.version>2.0.30.Final</netty-boringssl.version>
     <powermock.version>2.0.0-beta.5</powermock.version>
     <protobuf3.version>3.5.1</protobuf3.version>