[HOT-FIX] fix session middleware initialization

Author: pxpm

src/app/Http/Middleware/AuthenticateSession.php

@@ -2,8 +2,16 @@
 
 namespace Backpack\CRUD\app\Http\Middleware;
 
-if (class_exists('Illuminate\Contracts\Session\Middleware\AuthenticatesSessions', false)) {
+if (app()->version() >= 9.4) {
     class AuthenticateSession extends AuthenticateSessionL9
     {
     }
+} else {
+    class AuthenticateSession
+    {
+        public function handle($request, \Closure $next)
+        {
+            return $next($request);
+        }
+    }
 }