TwigUtil::$storage grows indefinitely

[malarzm]

Today I was looking for memory leaks in our application's test suite and found out that the storage in https://github.com/Payum/Core/blob/43954de6415e1a29fa09d7ca7949b071741afbc6/Bridge/Twig/TwigUtil.php#L9 keeps growing and is never cleared. This is not a big deal in a casual request-response lifecycle but is a big pain in a functional test suite. So far our solution is clearing the storage with our own class

<?php

declare(strict_types=1);

namespace App\Tests\Payum;

class TwigUtil extends \Payum\Core\Bridge\Twig\TwigUtil
{
    public static function clearStorage(): void
    {
        if (null === static::$storage) {
            return;
        }

        static::$storage->removeAll(static::$storage);
    }
}

which we call in tests' tearDown method however it'd be great to get rid of the memory leak at its source.