fix: 修改频道列表api的请求对象参数问题 (#15)

Co-authored-by: veehou <veehou@tencent.com>

qqbot/model/user.py

@@ -13,4 +13,4 @@ def __init__(self, before: str = None, after: str = None, limit: str = None):
 
         self.before = before
         self.after = after
-        self.limit = limit
+        self.limit = int(limit)