chore: Update typing import in flags.py

The typing import in flags.py has been updated to include the Optional module. This change ensures that the __commands_flag_positional__ attribute can accept a value of None.

Author: Vioshim

discord/ext/commands/flags.py

@@ -29,7 +29,7 @@
 import re
 import sys
 from dataclasses import dataclass, field
-from typing import TYPE_CHECKING, Any, Iterator, Literal, Pattern, TypeVar, Union
+from typing import TYPE_CHECKING, Any, Iterator, Literal, Optional, Pattern, TypeVar, Union
 
 from discord.utils import MISSING, MissingField, maybe_coroutine, resolve_annotation
 
@@ -294,7 +294,7 @@ class FlagsMeta(type):
         __commands_flag_case_insensitive__: bool
         __commands_flag_delimiter__: str
         __commands_flag_prefix__: str
-        __commands_flag_positional__: Flag | None
+        __commands_flag_positional__: Optional[Flag]
 
     def __new__(
         cls: type[type],