WP Inventory Version 1.9.6

I downloaded the new version of WP Inventory this morning but getting this message-

IMPORTANT!
Your server is using version 7.0.2-pl0-gentoo of PHP, which is over 6 years old, not maintained, and exposes your website to attack.
WP Inventory requires version 7.1 or higher, so it is not loaded.

I went to upgrade my PHP to the new version but don’t have the option. I think it’s because we are using a 2011 theme.

Is there a way I can go back to the 1.9.5 version? and NO of course I didn’t backup.