Require Jenkins 2.426.3 and latest parent pom (#18)

Also updates several items in the pom

Jenkinsfile

@@ -1,6 +1,10 @@
+/*
+ See the documentation for more options:
+ https://github.com/jenkins-infra/pipeline-library/
+*/
 buildPlugin(
-  useContainerAgent: true,
+  useContainerAgent: true, // Set to `false` if you need to use Docker for containerized tests
   configurations: [
-    [platform: 'linux', jdk: 8],
-    [platform: 'windows', jdk: 8],
+    [platform: 'linux', jdk: 21],
+    [platform: 'windows', jdk: 17],
 ])

pom.xml

@@ -4,7 +4,7 @@
   <parent>
     <groupId>org.jenkins-ci.plugins</groupId>
     <artifactId>plugin</artifactId>
-    <version>4.76</version>
+    <version>4.83</version>
   </parent>
 
   <artifactId>label-verifier</artifactId>
@@ -14,8 +14,7 @@
   <url>https://github.com/jenkinsci/label-verifier-plugin</url>
 
   <properties>
-    <jenkins.version>2.414.3</jenkins.version>
-    <java.level>8</java.level>
+    <jenkins.version>2.426.3</jenkins.version>
   </properties>
 
   <licenses>
@@ -41,8 +40,8 @@
   </developers>
 
     <scm>
-      <connection>scm:git:ssh://github.com/jenkinsci/${project.artifactId}-plugin.git</connection>
-      <developerConnection>scm:git:ssh://[email protected]/jenkinsci/${project.artifactId}-plugin.git</developerConnection>
+      <connection>scm:git:https://github.com/jenkinsci/${project.artifactId}-plugin.git</connection>
+      <developerConnection>scm:git:[email protected]:jenkinsci/${project.artifactId}-plugin.git</developerConnection>
       <url>https://github.com/jenkinsci/${project.artifactId}-plugin</url>
       <tag>HEAD</tag>
   </scm>
@@ -61,8 +60,3 @@
         </pluginRepository>
     </pluginRepositories>
 </project>  
-
-
-
-
-