Update Export to JDK 21 in git-gerrit-pull

Change-Id: I4c246190a7d260306f185b1819dd5391610578fd
diff --git a/bin/git_gerrit_pull b/bin/git_gerrit_pull
index 3782cec..9aa6c6f 100755
--- a/bin/git_gerrit_pull
+++ b/bin/git_gerrit_pull
@@ -116,7 +116,7 @@
 
 # KalamarExport-Plugin
 elsif ($project =~ m!^Kalamar-Plugin-Export$!i) {
-  _check('JAVA_HOME="'.$JAVA17_HOME.'" mvn clean test');
+  _check('JAVA_HOME="'.$JAVA21_HOME.'" mvn clean test');
 }
 
 # Koral