Correct parameter type on MakesHttpRequests:followRedirects() (#48557)

TestResponse does not directly extend Response, instead it uses @mixin and so must be hinted explicitly to not cause errors when analyzed.

src/Illuminate/Foundation/Testing/Concerns/MakesHttpRequests.php

@@ -684,7 +684,7 @@ protected function prepareCookiesForJsonRequest()
     /**
      * Follow a redirect chain until a non-redirect is received.
      *
-     * @param  \Illuminate\Http\Response  $response
+     * @param  \Illuminate\Http\Response|\Illuminate\Testing\TestResponse  $response
      * @return \Illuminate\Http\Response|\Illuminate\Testing\TestResponse
      */
     protected function followRedirects($response)