Reformat code using black

Segments where readability was hampered were fixed by appropriate
format skipping directives. New code should hopefully be black
compatible. The moment they remove the -S option is probably the moment
I stop using black though.

discord/mentions.py

@@ -25,9 +25,11 @@ DEALINGS IN THE SOFTWARE.
 from __future__ import annotations
 from typing import Type, TypeVar, Union, List, TYPE_CHECKING, Any, Union
 
+# fmt: off
 __all__ = (
     'AllowedMentions',
 )
+# fmt: on
 
 if TYPE_CHECKING:
     from .types.message import AllowedMentions as AllowedMentionsPayload