Use jenkins.baseline to reduce bom update mistakes (#104)

pom.xml

@@ -13,7 +13,9 @@
     <properties>
         <changelist>999999-SNAPSHOT</changelist>
         <gitHubRepo>jenkinsci/${project.artifactId}-plugin</gitHubRepo>
-        <jenkins.version>2.452.4</jenkins.version>
+        <!-- https://www.jenkins.io/doc/developer/plugin-development/choosing-jenkins-baseline/ -->
+        <jenkins.baseline>2.452</jenkins.baseline>
+        <jenkins.version>${jenkins.baseline}.4</jenkins.version>
     </properties>
     <name>Command Agent Launcher Plugin</name>
     <description>Allows agents to be launched using a specified command.</description>
@@ -46,7 +48,7 @@
         <dependencies>
             <dependency>
                 <groupId>io.jenkins.tools.bom</groupId>
-                <artifactId>bom-2.452.x</artifactId>
+                <artifactId>bom-${jenkins.baseline}.x</artifactId>
                 <version>3654.v237e4a_f2d8da_</version>
                 <type>pom</type>
                 <scope>import</scope>