Probably smart to make sure the tests can pass, too, + typo correction.

disco/types/message.py

@@ -346,7 +346,7 @@ class Message(SlottedModel):
         IDs for roles mentioned within this message.
     embeds : list[`MessageEmbed`]
         Embeds for this message.
-    attachments : list[`MessageAttachment`]
+    attachments : dict[`MessageAttachment`]
         Attachments for this message.
     reactions : list[`MessageReaction`]
         Reactions for this message.

tests/types/user.py

@@ -13,7 +13,7 @@ class TestChannel(TestCase):
             bot=False)
 
         self.assertEqual(
-            u.avatar_url, 'https://cdn.discordapp.com/avatars/12345/1234567890abcdefghijkl.webp?size=1024'
+            u.avatar_url, 'https://media.discordapp.net/avatars/12345/1234567890abcdefghijkl.webp?size=1024'
         )
 
     def test_user_default_avatar(self):