[NO-JIRA] Update enforcer-plugin to require building with JDK 21

Author: mattrpav

pom.xml

@@ -1149,8 +1149,8 @@
             <configuration>
               <rules>
                 <requireJavaVersion>
-                  <version>[17,)</version>
-                  <message>You must use Java 17+ to build.</message>
+                  <version>[21,)</version>
+                  <message>You must use Java 21+ to build.</message>
                 </requireJavaVersion>
               </rules>
             </configuration>