fix: update zhihu activity api url (#6745)

lib/routes/zhihu/activities.js

@@ -6,7 +6,7 @@ module.exports = async (ctx) => {
 
     const response = await got({
         method: 'get',
-        url: `https://www.zhihu.com/api/v4/members/${id}/activities?limit=7`,
+        url: `https://www.zhihu.com/api/v3/moments/${id}/activities?limit=7&desktop=true`,
         headers: {
             ...utils.header,
             Referer: `https://www.zhihu.com/people/${id}/activities`,