Use parent pom 4.60

mockito-inline was removed in mockito/mockito#2945, replaced with
mockito-core. Consumers of mockito-inline should replace their dependency
on mockito-inline with a dependency on mockito-core.

pom.xml

@@ -5,7 +5,7 @@
   <parent>
     <groupId>org.jenkins-ci.plugins</groupId>
     <artifactId>plugin</artifactId>
-    <version>4.59</version>
+    <version>4.60</version>
     <relativePath />
   </parent>