Explicitly setting content_type=None for responses without a body. #251

[nitpick] The accepted() method doesn't set a body, but the HttpResponse dataclass defaults content_type to "application/json". This could lead to a response with a Content-Type header but no body. Consider explicitly setting content_type=None for responses without a body.

        return HttpResponse(status_code=202, content_type=None)

Originally posted by @Copilot in #221 (comment)