Update parent POM, update dependencies, test with Java 21 (#48)

* Test with Java 21.

* Update parent POM.

* Update Jenkins version.

* Update BOM version.

Jenkinsfile

@@ -1 +1,11 @@
-buildPlugin(useContainerAgent: true)
+/*
+ See the documentation for more options:
+ https://github.com/jenkins-infra/pipeline-library/
+*/
+buildPlugin(
+  forkCount: '1C', // run this number of tests in parallel for faster feedback.  If the number terminates with a 'C', the value will be multiplied by the number of available CPU cores
+  useContainerAgent: true, // Set to `false` if you need to use Docker for containerized tests
+  configurations: [
+    [platform: 'linux', jdk: 21],
+    [platform: 'windows', jdk: 17],
+])

pom.xml

@@ -5,7 +5,7 @@
     <parent>
         <groupId>org.jenkins-ci.plugins</groupId>
         <artifactId>plugin</artifactId>
-        <version>4.50</version>
+        <version>4.74</version>
         <relativePath />
     </parent>
 
@@ -48,7 +48,7 @@
     <properties>
         <revision>1.17</revision>
         <changelist>-SNAPSHOT</changelist>
-        <jenkins.version>2.332.3</jenkins.version>
+        <jenkins.version>2.361.4</jenkins.version>
         <gitHubRepo>jenkinsci/${project.artifactId}-plugin</gitHubRepo>
         <cargo.version>1.7.6</cargo.version>
         <deployment-client.version>5.1.0</deployment-client.version>
@@ -58,8 +58,8 @@
         <dependencies>
             <dependency>
                 <groupId>io.jenkins.tools.bom</groupId>
-                <artifactId>bom-2.332.x</artifactId>
-                <version>1670.v7f165fc7a_079</version>
+                <artifactId>bom-2.361.x</artifactId>
+                <version>2102.v854b_fec19c92</version>
                 <scope>import</scope>
                 <type>pom</type>
             </dependency>