Urgent Fix for issue Content Type not specified (#31533)

This fixes issue #31518 where Laravel isn't setting a Content-Type and so Symfony is just setting it to whatever the request is asking for.  This is poisoning our cache, serving up our website HTML pages as "XML".

src/Illuminate/Routing/Router.php

@@ -746,7 +746,7 @@ public static function toResponse($request, $response)
                     is_array($response))) {
             $response = new JsonResponse($response);
         } elseif (! $response instanceof SymfonyResponse) {
-            $response = new Response($response);
+            $response = new Response($response, 200, ['Content-Type' => 'text/html']);
         }
 
         if ($response->getStatusCode() === Response::HTTP_NOT_MODIFIED) {