WooCommerce Lightspeed POS Integration 2.16.7

* Fix - Fixes a "PHP Parse error: syntax error, unexpected ')'" for user using PHP 7.2
* Fix - Fixes duplicate background jobs from showing up in the action scheduler

New - Adds support for persistent cache (Memcached or Redis)

* Fix - Fixes a category import bug where categories of with the same name are assigned to the incorrect products
* Fix - Fixes a bug where Webstore properties (long, short, LxWxH) were not being synced from WC->LS correctly
* Fix - MySQL bugfix for versions > 8.0. The "system" column in the wclsi_attribute_sets table is a reserved keyword. Renames the column to "sys".
* Tweak - Ensure attributes are updated every 30s
* Tweak - Adds a register_taxonomy() call for new product attributes, this ensures attribute taxonomies are created instantly
* New - Fixes up PHPUnit tests. Automated tests are now run on every new commit, PR, and before every release.