[9.x] Fix Precognition headers for Symfony responses

[timacdonald]

The $response->header() function is only available on Laravel responses. This PR fixes usage with Symfony responses, such as BinaryFileResponse.

[bert-w]

But the docblock says @param \Illuminate\Http\Request $request? Is it intended to somehow use this middleware with Symfony requests?

[driesvints]

@bert-w a symfony response can still be sent out instead of a Illuminate http response.