Bump java.version from 8 to 11

Author: simonsymhoven

pom.xml

@@ -20,7 +20,7 @@
         <changelist>-SNAPSHOT</changelist>
         <jenkins.baseline>2.319</jenkins.baseline>
         <jenkins.version>${jenkins.baseline}.3</jenkins.version>
-        <java.level>8</java.level>
+        <java.level>11</java.level>
         <gitHubRepo>jenkinsci/${project.artifactId}-plugin</gitHubRepo>
         <select2.version>4.0.13</select2.version>