[fit] upgrade netty from 4.2.2.Final to 4.2.6.Final

Author: CodeCasterX

framework/fit/java/fit-builtin/plugins/fit-http-server-netty/pom.xml

@@ -18,7 +18,7 @@
 
     <properties>
         <!-- Third-party versions -->
-        <netty.version>4.2.2.Final</netty.version>
+        <netty.version>4.2.6.Final</netty.version>
     </properties>
 
     <dependencies>