WooCommerce Product Search 6.1.0

* WordPress 5.6 compatible.
* WooCommerce 4.8 compatible.
* Requires at least WooCommerce 3.5.
* Updated upgrade info.

* WordPress 5.5 compatible.
* WooCommerce 4.7 compatible.
* Requires at least WooCommerce 3.3.
* Added the WPS_DEFER_VARIATIONS_THRESHOLD constant that regulates the maximum number of variations processed at save.
* Solved issues when indexing variable products with many variations by using deferred processing of the bulk of variations.
* Fixed "Text for no selection" option was not visible when Select was chosen as Style in Category and Attribute filter widgets.

* WordPress 5.5 compatible.
* WooCommerce 4.6 compatible.
* Added support for filtering the results presented by the [products] shortcode.
* Added the WPS_SHORTCODES_PRODUCTS_FILTER constant which when set as true enables automatic filtering of all instances of the [products] shortcode.
* Added the [woocommerce_product_search_filter_shortcode_products] shortcode.
* Added the woocommerce_product_search_filter_shortcode_products() API function.
* Added the woocommerce_product_search_filter_shortcode_products_enable() API function.
* Added the woocommerce_product_search_filter_shortcode_products_disable() API function.
* Added the woocommerce_product_search_filter_shortcode_products filter.
* Added automatic support for filtering the results presented by the Divi Shop module.
* Added the WPS_DIVI_SHOP_FILTER constant which when set as false disables automatic filtering of all instances of the Divi Shop module.
* Added the woocommerce_product_search_filter_divi_shop filter.
* Fixed issues with our price filter and WPML multicurrency.
* Fixed price filter range issues for variable products so that in-between values are treated correctly and bring up results.
* Fixed a missing check for array type to prevent warning related to Countable.