chore: Upgrade to latest LTS core version supporting Java 8 (requires 2.346.3)

Author: gounthar

pom.xml

@@ -5,16 +5,18 @@
   <parent>
     <groupId>org.jenkins-ci.plugins</groupId>
     <artifactId>plugin</artifactId>
-    <version>4.34</version>
+    <version>4.51</version>
+    <relativePath />
   </parent>
   <groupId>org.jenkins-ci.plugins</groupId>
   <artifactId>gogs-webhook</artifactId>
   <version>1.0.16-SNAPSHOT</version>
   <packaging>hpi</packaging>
 
   <properties>
-    <jenkins.version>2.289.1</jenkins.version>
-    <java.level>8</java.level>
+    <!-- https://www.jenkins.io/doc/developer/plugin-development/choosing-jenkins-baseline/ -->
+    <jenkins.baseline>2.346</jenkins.baseline>
+    <jenkins.version>${jenkins.baseline}.3</jenkins.version>
     <java.level.test>8</java.level.test>
     <findbugs.failOnError>false</findbugs.failOnError>
   </properties>
@@ -31,19 +33,12 @@
     </license>
   </licenses>
 
-  <developers>
-    <developer>
-      <id>sanderv32</id>
-      <name>Alexander Verhaar</name>
-    </developer>
-  </developers>
-
   <dependencyManagement>
     <dependencies>
       <dependency>
         <groupId>io.jenkins.tools.bom</groupId>
-        <artifactId>bom-2.289.x</artifactId>
-        <version>961.vf0c9f6f59827</version>
+        <artifactId>bom-${jenkins.baseline}.x</artifactId>
+        <version>1763.v092b_8980a_f5e</version>
         <type>pom</type>
         <scope>import</scope>
       </dependency>
@@ -91,7 +86,6 @@
     <dependency>
       <groupId>junit</groupId>
       <artifactId>junit</artifactId>
-      <version>4.13.2</version>
       <scope>test</scope>
       <exclusions>
         <exclusion>