Bump io.netty:netty-bom from 4.2.7.Final to 4.2.8.Final

Bumps [io.netty:netty-bom](https://github.com/netty/netty) from 4.2.7.Final to 4.2.8.Final.
- [Commits](netty/netty@netty-4.2.7.Final...netty-4.2.8.Final)

---
updated-dependencies:
- dependency-name: io.netty:netty-bom
  dependency-version: 4.2.8.Final
  dependency-type: direct:production
  update-type: version-update:semver-patch
...

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

Author: dependabot[bot]

ui-tests/pom.xml

@@ -38,7 +38,7 @@
         <!-- ClassNotFoundException if omitted -->
         <groupId>io.netty</groupId>
         <artifactId>netty-bom</artifactId>
-        <version>4.2.7.Final</version>
+        <version>4.2.8.Final</version>
         <type>pom</type>
         <scope>import</scope>
       </dependency>