Update messages.json

Author: ImprovedTube

_locales/zh_CN/messages.json

@@ -217,7 +217,7 @@
     },
     "Dim Youtube's Pages, except what I mouse-over!": {
         "message": "在当前页面上模糊除鼠标所在位置外的其他元素"
-    }
+    },
     "empty": {
         "message": "暂无"
     },