Bump jetty-server in /adapters/spi/jetty-adapter-spi

Bumps [jetty-server](https://github.com/eclipse/jetty.project) from 8.1.17.v20150415 to 9.4.51.v20230217.
- [Release notes](https://github.com/eclipse/jetty.project/releases)
- [Commits](jetty/jetty.project@jetty-8.1.17.v20150415...jetty-9.4.51.v20230217)

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

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

adapters/spi/jetty-adapter-spi/pom.xml

@@ -32,7 +32,7 @@
         <maven.compiler.target>1.7</maven.compiler.target>
         <maven.compiler.source>1.7</maven.compiler.source>
 
-        <jetty9.version>8.1.17.v20150415</jetty9.version>
+        <jetty9.version>9.4.51.v20230217</jetty9.version>
         <keycloak.osgi.export>
             org.keycloak.adapters.jetty.spi.*
         </keycloak.osgi.export>