fix7: line 511,change if condition

-n 取非，初看不容易理解，

install-release.sh

@@ -508,8 +508,8 @@ main() {
   fi
 
   # Determine if V2Ray is running
-  if [[ -n "$(systemctl list-unit-files | grep 'v2ray')" ]]; then
-    if [[ -n "$(pidof v2ray)" ]]; then
+  if systemctl list-unit-files | grep -q 'v2ray'; then
+    if pidof v2ray; then
       stop_v2ray
       V2RAY_RUNNING='1'
     fi