Merge pull request #22 from jenkinsci/update-parent-pom

Updates parent pom to 4.51

Author: froque

pom.xml

@@ -3,7 +3,7 @@
   <parent>
     <groupId>org.jenkins-ci.plugins</groupId>
     <artifactId>plugin</artifactId>
-    <version>3.53</version>
+    <version>4.51</version>
   </parent>
 
   <artifactId>powershell</artifactId>