Vendor: Remove brumann/polyfill-unserialize

> In case you are using PHP 7.0+ the original unserialize() will be used instead.

composer.json

@@ -48,7 +48,6 @@
         "ext-zlib": "*",
         "angelfqc/vimeo-api": "2.0.6",
         "apereo/phpcas": "^1.6",
-        "brumann/polyfill-unserialize": "^1.0",
         "chamilo/pclzip": "~2.8",
         "clue/graph": "~0.9.0",
         "culqi/culqi-php": "1.3.4",

main/inc/lib/UnserializeApi.php

@@ -1,8 +1,6 @@
 <?php
 /* For licensing terms, see /license.txt */
 
-use Brumann\Polyfill\Unserialize;
-
 /**
  * Class UnserializeApi.
  */
@@ -109,13 +107,13 @@ class UnserializeApi
         }
 
         if ($ignoreErrors) {
-            return @Unserialize::unserialize(
+            return @unserialize(
                 $serialized,
                 ['allowed_classes' => $allowedClasses]
             );
         }
 
-        return Unserialize::unserialize(
+        return unserialize(
             $serialized,
             ['allowed_classes' => $allowedClasses]
         );