0.4.0

Fixes

• Updated default_key in RatelimitIO.__init__ to default to None instead of "unknown_key", ensuring kwargs["ip"] is used when unique_key and default_key are not provided.
• Renamed _prepare_key_and_limit to _prepare_key for clarity.
• Refactored _prepare_key to simplify logic and resolve inconsistencies in key generation.
• Fixed key handling in wait and a_wait to correctly validate and apply rate limits.
• Ensured proper rate-limiting behavior for async and sync decorators with function-specific keys.
• Addressed issues causing NoneType errors when limit_spec was not provided in wait and a_wait.

Misc

• Enhanced key generation with async/sync-specific prefixes to distinguish between function call types.
• Updated virtualenv dependency from 20.28.1 to 20.29.0 via poetry update.