Update package version to 21.0.9+4

pkg.info

@@ -1,6 +1,6 @@
 name: openjdk-21
 description: OpenJDK Java 21
-version: 21.0.6+7
+version: 21.0.9+4
 url: https://openjdk.org/
 license: GPL2-only WITH Classpath-exception-2.0
 architecture: any

post_install.sh

@@ -1,4 +1,4 @@
 #!/bin/bash
 
 # Set default java version if not already set
-[ -d "$BPM_ROOT"/usr/lib/java/default/bin ] || ln -sf openjdk-21 -T "$BPM_ROOT"/usr/lib/java/default
+[ -d /usr/lib/java/default/bin ] || ln -sf openjdk-21 -T /usr/lib/java/default