add the exit code for ragstack-release tag rev-parse check

Author: zzzming

ragstack/ragstack-release.sh

@@ -33,6 +33,7 @@ echo "Identified remote $remote_name"
 
 if git rev-parse $tag >/dev/null 2>&1; then
     echo "Git tag $tag already exists"
+    exit 1
 fi
 
 cd $directory