chore(CI): fix build error when no have base upgrade package

.ci/build_packages/tests.sh

@@ -153,8 +153,9 @@ relup_test(){
     if [ -d "${RELUP_PACKAGE_PATH}" ];then
         cd "${RELUP_PACKAGE_PATH}"
 
-        for var in "${EMQX_NAME}"-*-"${ARCH}".zip;do
-            packagename=$(basename "${var}")
+        find . -maxdepth 1 -name "${EMQX_NAME}-*-${ARCH}.zip" |
+            while read -r pkg; do
+                packagename=$(basename "${pkg}")
                 unzip "$packagename"
                 ./emqx/bin/emqx start || ( tail emqx/log/emqx.log.1 && exit 1 )
                 ./emqx/bin/emqx_ctl status