Make getCookie public so it can be directly used in tests (laravel#38524

)

src/Illuminate/Testing/TestResponse.php

@@ -523,7 +523,7 @@ public function assertCookieMissing($cookieName)
      * @param  string  $cookieName
      * @return \Symfony\Component\HttpFoundation\Cookie|null
      */
-    protected function getCookie($cookieName)
+    public function getCookie($cookieName)
     {
         foreach ($this->headers->getCookies() as $cookie) {
             if ($cookie->getName() === $cookieName) {