Features
- Added a new `InternalServerError` exception for unexpected errors.
- The `utils.py` file now contains helper functions that can be used outside the `Netcord` class.
- The `login_required` function is used to extract an access token from the `Authorization` header, as well as checking for its presence.
- The `extract_callback_data` function is used to quickly and conveniently extract all necessary information from the request body after successful authorization and redirect to `/callback`.