Bump jetty-webapp in /specrunner-jetty

Bumps [jetty-webapp](https://github.com/eclipse/jetty.project) from 9.3.27.v20190418 to 9.4.34.v20201102.
- [Release notes](https://github.com/eclipse/jetty.project/releases)
- [Commits](jetty/jetty.project@jetty-9.3.27.v20190418...jetty-9.4.34.v20201102)

---
updated-dependencies:
- dependency-name: org.eclipse.jetty:jetty-webapp
  dependency-type: direct:production
...

Signed-off-by: dependabot[bot] <support@github.com>

Author: dependabot[bot]

specrunner-jetty/pom.xml

@@ -22,7 +22,7 @@
     </distributionManagement>
 
 	<properties>
-		<jetty.version>9.3.27.v20190418</jetty.version>
+		<jetty.version>9.4.34.v20201102</jetty.version>
 		<jasper.version>6.0.45</jasper.version>
 		<jstl.version>1.2</jstl.version>
 	</properties>