Use jenkins.baseline to reduce bom update mistakes (#81)

pom.xml

@@ -12,7 +12,9 @@
     <packaging>hpi</packaging>
     <properties>
         <changelist>999999-SNAPSHOT</changelist>
-        <jenkins.version>2.440.3</jenkins.version>
+        <!-- https://www.jenkins.io/doc/developer/plugin-development/choosing-jenkins-baseline/ -->
+        <jenkins.baseline>2.440</jenkins.baseline>
+        <jenkins.version>${jenkins.baseline}.3</jenkins.version>
         <gitHubRepo>jenkinsci/${project.artifactId}-plugin</gitHubRepo>
     </properties>
     <name>Oracle Java SE Development Kit Installer Plugin</name>
@@ -45,7 +47,7 @@
         <dependencies>
             <dependency>
                 <groupId>io.jenkins.tools.bom</groupId>
-                <artifactId>bom-2.440.x</artifactId>
+                <artifactId>bom-${jenkins.baseline}.x</artifactId>
                 <version>3234.v5ca_5154341ef</version>
                 <type>pom</type>
                 <scope>import</scope>