Change JSON based HttpResponse to JSONResponse

[Andrew-Chen-Wang]

https://github.com/jazzband/django-oauth-toolkit/blob/d90bb348f00886ae8321f8194f6275be9aa08f80/oauth2_provider/views/introspect.py#L48-L56

Any reason not to use django.http.JSONResponse?

[auvipy]

valid point to use jsonresponse