Fix user update regression (fix #844)

Author: dolfies

discord/user.py

@@ -1040,6 +1040,7 @@ def _update_self(self, user: Union[PartialUserPayload, Tuple[()]]) -> Optional[T
                 self._public_flags,
                 self._avatar_decoration_data,
                 self.global_name,
+                self._primary_guild,
             ) = modified
             # Signal to dispatch user_update
             return to_return, self