half a (syntax error, unexpected ‘:’)

Ok so Ive been trying to figure this out for a few hours now. The address Hollymgraham.com is parked in a folder on Jdgraham.net (specifically jdgraham.net/hmgillustration) I updated woo commerce this morning and it now gives a error (seen below) when you go to the hollymgraham.com address but not if you go to the jdgraham.net/hmgillustration address.

PHP Parse error: syntax error, unexpected ‘:’, expecting ‘{‘ in /var/www/vhosts/jdgraham.net/httpdocs/hmgillustration/wp-content/plugins/woocommerce/woocommerce.php on line 56

I have dug through line 56 Seen here
function wc_get_container() : \Psr\Container\ContainerInterface {

I am nervous to reinstall woocommerce and loose the shop and its contents. I dont know what to do as customers for the site cant get to it through the normal link.
Please help and advise.

I am running the latest WP and the latest woocommerce on both the jdgraham.net site and the subfolder site. I have tried a number of solutions from other issues like this in the support forum with no success. It just doesnt make sense why its working on one and not the other. Please help.

The page I need help with: [log in to see the link]