Minor Improvement: Add Java 20 version to assertJavaCheckPasses() in …

…war>src>test (jenkinsci#8285)

* Add java 20 version to assertJavaCheckPasses() in war>src>test

* Discard changes to war/yarn.lock

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Co-authored-by: Pushkar-Mahajan4 <pushkarmahajan1027@gmail.com>
Co-authored-by: Tim Jacomb <21194782+timja@users.noreply.github.com>

war/src/test/java/executable/MainTest.java

@@ -28,13 +28,15 @@ void future() {
         assertJavaCheckFails(16, false);
         assertJavaCheckFails(18, false);
         assertJavaCheckFails(19, false);
+        assertJavaCheckFails(20, false);
         assertJavaCheckPasses(12, true);
         assertJavaCheckPasses(13, true);
         assertJavaCheckPasses(14, true);
         assertJavaCheckPasses(15, true);
         assertJavaCheckPasses(16, true);
         assertJavaCheckPasses(18, true);
         assertJavaCheckPasses(19, true);
+        assertJavaCheckPasses(20, true);
     }
 
     private static void assertJavaCheckFails(int releaseVersion, boolean enableFutureJava) {