Bump org.eclipse.jetty:jetty-servlet from 9.4.42.v20210604 to 11.0.18

Bumps [org.eclipse.jetty:jetty-servlet](https://github.com/eclipse/jetty.project) from 9.4.42.v20210604 to 11.0.18.
- [Release notes](https://github.com/eclipse/jetty.project/releases)
- [Commits](jetty/jetty.project@jetty-9.4.42.v20210604...jetty-11.0.18)

---
updated-dependencies:
- dependency-name: org.eclipse.jetty:jetty-servlet
  dependency-type: direct:production
  update-type: version-update:semver-major
...

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

build.gradle

@@ -365,7 +365,7 @@ dependencies {
 
     // webserver for old webapp that is scheduled for removal
     implementation 'org.eclipse.jetty:jetty-server:9.4.42.v20210604'
-    implementation 'org.eclipse.jetty:jetty-servlet:9.4.42.v20210604'
+    implementation 'org.eclipse.jetty:jetty-servlet:11.0.18'
     implementation 'org.eclipse.jetty:jetty-webapp:9.4.42.v20210604'
     implementation 'org.eclipse.jetty:jetty-continuation:9.4.42.v20210604'
     implementation 'org.eclipse.jetty.websocket:websocket-client:9.4.42.v20210604'