Possible to add "canonical tag" to categories?

Hi,

Im using categories in my shop to separate different articles of clothing (tees, hoodies, caps, etc).

For example "https://www.duhvoli.com/shop/hoodies" is a category page for all my hoodies.

Google is ignoring these urls and suggests I  "Alternate pages with proper canonical tag"

(it choses the first product page under said category instead)

How can I add canonical tag to category page? 

If it's not possible, what would be best solution to fix this?

Thanks! 

I'm having same issue