Bump io.netty:netty from 3.6.6.Final to 3.9.8.Final in /tajo-project

Bumps [io.netty:netty](https://github.com/netty/netty) from 3.6.6.Final to 3.9.8.Final.
- [Commits](https://github.com/netty/netty/compare/netty-3.6.6.Final...netty-3.9.8.Final)

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

Signed-off-by: dependabot[bot] <support@github.com>
diff --git a/tajo-project/pom.xml b/tajo-project/pom.xml
index 59628a9..f27ba57 100644
--- a/tajo-project/pom.xml
+++ b/tajo-project/pom.xml
@@ -846,7 +846,7 @@
       <dependency>
         <groupId>io.netty</groupId>
         <artifactId>netty</artifactId>
-        <version>3.6.6.Final</version>
+        <version>3.9.8.Final</version>
       </dependency>
       <dependency>
         <groupId>joda-time</groupId>