ZOOKEEPER-3794: upgrade netty to address CVE-2020-11612

Latest owasp runs are flagging this. Simple upgrade to the current latest version of netty 4.1.x codeline.

Change-Id: I3defe8a731a2bf22abbd154e7d51054cb62aaa64

Author: Patrick Hunt <phunt@apache.org>

Reviewers: Enrico Olivelli <eolivelli@apache.org>

Closes #1319 from phunt/ZOOKEEPER-3794

pom.xml

@@ -353,7 +353,7 @@
     <mockito.version>2.27.0</mockito.version>
     <hamcrest.version>1.3</hamcrest.version>
     <commons-cli.version>1.2</commons-cli.version>
-    <netty.version>4.1.45.Final</netty.version>
+    <netty.version>4.1.48.Final</netty.version>
     <jetty.version>9.4.24.v20191120</jetty.version>
     <jackson.version>2.10.3</jackson.version>
     <json.version>1.1.1</json.version>