bump org.jenkins-ci.plugins:plugin to 1.596.1

Author: Frode Aannevik

pom.xml

@@ -3,7 +3,7 @@
   <parent>
     <groupId>org.jenkins-ci.plugins</groupId>
     <artifactId>plugin</artifactId>
-    <version>1.509.4</version><!-- which version of Jenkins is this plugin built against? -->         
+    <version>1.596.1</version>
   </parent>
 
   <artifactId>bitbucket-pullrequest-builder</artifactId>