Online_Shop_Theme_Info::$notification is deprecated

Please help, how to solve the below issue:

PHP Deprecated: Creation of dynamic property Online_Shop_Theme_Info::$notification is deprecated in /home/u318971811/domains/labtexbd.com/public_html/wp-content/themes/online-shop/acmethemes/at-theme-info/class-at-theme-info.php on line 49

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