feature: Return error response on auth failure with redirect disabled

[alirf81]

Hi @greenpau
While using caddy-security, I found this error.
greenpau/caddy-security#157 (comment)
So I disabled redirect in caddy security and when I put no token, it returned 500 Internal Server Error.
As I checked, this is because of go-authcrunch package.
https://github.com/greenpau/go-authcrunch/blob/main/pkg/authz/authenticate.go#L123
Here, if there is an error and redirect is disabled, it sets nothing in response writer.
As a result, Caddy caused the internal server error.
Can you please make it set some error response if redirect disabled? and release new tag of go-authcrunch and caddy-security?
It will be very helpful to me!
Thank you