Make Tab object transient (#11219)

Author: janfaracik

core/src/main/java/jenkins/model/Tab.java

@@ -43,7 +43,7 @@
  */
 public abstract class Tab implements Action, Badgeable {
 
-    protected Actionable object;
+    protected transient Actionable object;
 
     public Tab(Actionable object) {
         this.object = object;