fix: add avatar_url to user Mixins (#1528)

* fix: add avatar_url to user mixins

* fix: add avatar_url property to Mixins

* chore: remove avatar_url from Member class

Author: maksims8

interactions/models/discord/user.pyi

@@ -52,6 +52,8 @@ class FakeBaseUserMixin(DiscordObject, _SendDMMixin):
     def display_name(self) -> str: ...
     @property
     def display_avatar(self) -> Asset: ...
+    @property
+    def avatar_url(self) -> str: ...
     async def fetch_dm(self, *, force: bool) -> DM: ...
     def get_dm(self) -> Optional["DM"]: ...
     @property