Bump jetty.version from 11.0.17 to 11.0.20

Bumps `jetty.version` from 11.0.17 to 11.0.20.

Updates `org.eclipse.jetty:jetty-server` from 11.0.17 to 11.0.20

Updates `org.eclipse.jetty:jetty-webapp` from 11.0.17 to 11.0.20

Updates `org.eclipse.jetty:jetty-maven-plugin` from 11.0.17 to 11.0.20

---
updated-dependencies:
- dependency-name: org.eclipse.jetty:jetty-server
  dependency-type: direct:production
  update-type: version-update:semver-patch
- dependency-name: org.eclipse.jetty:jetty-webapp
  dependency-type: direct:production
  update-type: version-update:semver-patch
- dependency-name: org.eclipse.jetty:jetty-maven-plugin
  dependency-type: direct:production
  update-type: version-update:semver-patch
...

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

pom.xml

@@ -66,7 +66,7 @@
         <doxia.version>1.0</doxia.version>
         <!-- Note: closure-compiler -unshaded v20200920 (until at least v20210907) contains gson -->
         <google-closure.version>v20230802</google-closure.version>
-        <jetty.version>11.0.17</jetty.version>
+        <jetty.version>11.0.20</jetty.version>
         <jquerypp.version>1.0.1</jquerypp.version>
         <jquery.version>3.7.1</jquery.version>
         <junit-jupiter.version>5.10.0</junit-jupiter.version>