Memory leak on update array

[sergeyklay]

After fix 1f6962d#commitcomment-35331987

I still see memory leak.

manual.php

<?php

use Test\Properties\PropertyUpdate;

$t = new PropertyUpdate();
$t->p1 = [111];
$t->update1();

$ php -d extension=ext/modules/test.so manual.php
[Thu Oct  3 00:17:59 2019]  Script:  '/mnt/work/zephir/php-zephir/manual.php'
/home/klay/.phpenv/versions/7.2.20-zts-debug/include/php/Zend/zend_string.h(134) :  Freeing 0x00007f2309801dc0 (32 bytes), script=/mnt/work/zephir/php-zephir/manual.php
=== Total 1 memory leaks detected ===

$ php -v
PHP 7.2.20 (cli) (built: Jul 14 2019 17:30:04) ( ZTS DEBUG )
Copyright (c) 1997-2018 The PHP Group
Zend Engine v3.2.0, Copyright (c) 1998-2018 Zend Technologies
    with Zend OPcache v7.2.20, Copyright (c) 1999-2018, by Zend Technologies

Refs: #1915, #1918

/cc @chrysanthemum

[chrysanthemum]

I try to solve～