Stop testing Java 11 (#115)

Jenkinsfile

@@ -3,8 +3,9 @@
  https://github.com/jenkins-infra/pipeline-library/
 */
 buildPlugin(
-  useContainerAgent: true,
+  forkCount: '1C', // run this number of tests in parallel for faster feedback.  If the number terminates with a 'C', the value will be multiplied by the number of available CPU cores
+  useContainerAgent: true, // Set to `false` if you need to use Docker for containerized tests
   configurations: [
-    [platform: 'linux', jdk: 11], // use 'docker' if you have containerized tests
-    [platform: 'windows', jdk: 11]
+    [platform: 'linux', jdk: 21],
+    [platform: 'windows', jdk: 17],
 ])