Polylang Pro 3.6.1

* Pro: Fix conflict with JetThemesCore from Crocoblock
* Fix: better detection of REST requests when using plain permalinks
* Fix usage of deprecated action wpmu_new_blog in WP 5.1+
* Fix PHP notices with PHP 7.4

* Require PHP 5.6
* Fix PHP warning in WP 5.3

* Pro: Fix wrong ajax url when using one domain per language
* Pro: Fix conflict with user switching plugin when using multiple domains
* Pro: Fix latest posts block in WP 5.3
* Fix database error when attempting to sync an untranslated page parent
* Fix a conflict with the theme Neptune by Osetin