Removed unused variables in routes.

discord/http.py

@@ -368,7 +368,6 @@ class HTTPClient:
         return self.request(r)
 
     def logs_from(self, channel_id, limit, before=None, after=None, around=None):
-        url = '{0.CHANNELS}/{1}/messages'.format(self, channel_id)
         params = {
             'limit': limit
         }