Hi,
HikaShop doesn't include any Square payment plugin. If you have a Square payment plugin, it means that you installed it separately from HikaShop. And thus, you need to update it separately. If you've never updated it, it means you have a really old version of the plugin and thus you should update it.
I can see you purchased it in 2019 on our website. So go in the menu My account>My orders, open the order for that plugin, and you'll find the download link for the latest version next to the name of the plugin. Download it, and install it on your website and you'll have the latest version. Then, please test again.