Polylang Pro 3.6.4

* Improve performance in the pages (or hierarchical post types) list table
* Fix an ajax conflict with WooCommerce License manager

* Fix a warning when a language is corrupted in database (term_language missing)
* Fix confirmation modal with WooCommerce and WordPress < 5.6
* Fix an ajax conflict with WooCommerce Tree Table Rate Shipping and HubSpot All-In-One Marketing

* Move hreflang attributes higher in the head section #771
* Fix custom flags not working (introduced in 3.0)
* Fix translation of the confirmation modal when changing the language of a post
* Fix js and css not loaded when Polylang is used as a mu-plugin ((introduced in 3.0))
* Fix support for html5 stylesheet link tags #775
* Fix possible warning in frontend-filters-links.php
* Yoast SEO Premium: Take over the multilingual compatibility removed in Yoast SEO Premium 15.8 #796
* Yoast SEO: Fix CPT breadcrumb title when the option is left empty #794
* Yoast SEO: Fix sitemap.xml not redirected on secondary domains #789