Bump jetty in /unreleased/samples/helloworld-rest-contribution

Bumps jetty from 6.1.19 to 6.1.23.

---
updated-dependencies:
- dependency-name: org.mortbay.jetty:jetty
  dependency-type: direct:development
...

Signed-off-by: dependabot[bot] <support@github.com>
diff --git a/unreleased/samples/helloworld-rest-contribution/pom.xml b/unreleased/samples/helloworld-rest-contribution/pom.xml
index d1ebb70..efdea5e 100644
--- a/unreleased/samples/helloworld-rest-contribution/pom.xml
+++ b/unreleased/samples/helloworld-rest-contribution/pom.xml
@@ -79,7 +79,7 @@
       <dependency>
           <groupId>org.mortbay.jetty</groupId>
           <artifactId>jetty</artifactId>
-          <version>6.1.19</version>
+          <version>6.1.23</version>
           <scope>test</scope>
       </dependency>