Use jenkins.baseline to reduce bom update mistakes (#101)

Author: strangelookingnerd

pom.xml

@@ -14,7 +14,9 @@
   <packaging>hpi</packaging>
   <properties>
     <changelist>999999-SNAPSHOT</changelist>
-    <jenkins.version>2.263.1</jenkins.version>
+    <!-- https://www.jenkins.io/doc/developer/plugin-development/choosing-jenkins-baseline/ -->
+    <jenkins.baseline>2.263</jenkins.baseline>
+    <jenkins.version>${jenkins.baseline}.1</jenkins.version>
     <java.level>8</java.level>
     <gitHubRepo>jenkinsci/${project.artifactId}-plugin</gitHubRepo>
     <git-code-format-maven-plugin.version>4.3</git-code-format-maven-plugin.version>
@@ -26,7 +28,7 @@
     <dependencies>
       <dependency>
         <groupId>io.jenkins.tools.bom</groupId>
-        <artifactId>bom-2.263.x</artifactId>
+        <artifactId>bom-${jenkins.baseline}.x</artifactId>
         <version>961.vf0c9f6f59827</version>
         <scope>import</scope>
         <type>pom</type>