WooCommerce Min/Max Quantities 5.0.4

* Add - Quantity attribute to add to cart link.
* Fix - Wrong quantity calculation when both group of quantity setting and minimum setting are set.

* Fix - Ensure total quantity number is accurate in the minimum quantity error message.
* Fix - Update label and description of ""Allow Combination" option.
* Tweak - Update labels for the "Do not count" and "Exclude" options.
* Tweak - WC 5.4 compatibility.
* Tweak - WP 5.7 compatibility.

* Fix - Ensure that when on a Grouped Product page, all products can have their quantity set to zero, even if a product has a "Group of" value set.
* Fix - Make sure "Do not count" and "Exclude" rules are taken into account when there are existing products in the cart and new products are added.
* Fix - On variable products, ensure the "Allow Combination" setting is properly handled.
* Fix - add minimum and step values to all number inputs in the admin, to avoid being able to enter negative numbers.
* Fix - ensure we have terms before trying to use them.
* Tweak - add error notice if WooCommerce isn't active.
* Update - Standardize format and copy of error messages.