[lint] Remove extra whitespace in guild.py

Remove trailing whitespace in guild.py introduced by 3727ea9.

discord/guild.py

@@ -434,7 +434,7 @@ class Guild(Hashable):
             return ''
 
         return 'https://cdn.discordapp.com/icons/{0.id}/{0.icon}.{1}?size={2}'.format(self, format, size)
-    
+
     @property
     def splash_url(self):
         """Returns the URL version of the guild's invite splash. Returns an empty string if it has no splash."""