Polylang Pro 3.6.4

* Pro: Fix infinite loop with WP 6.6 when the locale fallbacks include the main locale of a language
* Pro: Prevent saving the main locale among the locale fallbacks of a language
* Pro: Hide the characters consumption graph when the DeepL cost control is deactivated
* Add Yoast SEO social title and social description to the strings translations
* Fix incorrect page on front and page for posts translations when the option is saved with admin language filter active

* Pro: Fix locale fallback for translations loaded just in time (requires WP 6.6)
* Allow to pass an array as context to icl_register_string() #1497
* Fix admin bar search menu in WP 6.6 #1496
* Fix a regression in the usage of the filter pll_flag #1489

* Pro: Fix XLIFF files not correctly imported when exported from older version than 3.6
* Pro: Fix translated categories not assigned to translated post when using machine translation
* Pro: Fix 'lang' param not applied for secondary queries during a REST request
* Pro: Fix newlines for content edited in classic editor and translated with DeepL
* Pro: Fix a conflict with the Stream plugin on multisite