Use Java 21 for Koral

Change-Id: I735330338ccbf390a242e4aa66c17a9dfd0e26fd
diff --git a/bin/git_gerrit_pull b/bin/git_gerrit_pull
index ae1e7b1..c361e49 100755
--- a/bin/git_gerrit_pull
+++ b/bin/git_gerrit_pull
@@ -75,7 +75,7 @@
 
 # Koral
 elsif ($project =~ m!^Koral$!i) {
-  _check('JAVA_HOME="'.$JAVA17_HOME.'" mvn clean test');
+  _check('JAVA_HOME="'.$JAVA21_HOME.'" mvn clean test');
 }
 
 # Krill