WooCommerce Lightspeed POS Integration 2.15.1

* New - New feature "Delete Lightspeed categories cache" - remove any LS categories in the cache. Forces the plugin to stop trying to link products' categories with ones that were imported.
* New - New "wclsi_sync_prod_inventory" filter that filters the $wc_prod object before syncing its inventory to Lightspeed
* Fix - Fixes a bug that was introduced in 1.6.8 that does not re-load the "wclsi_poll" action scheduler job
* Tweak - Enhances error and notification experience

* Fix - Fixes a bug where stores with duplicate SKU products were not being updated via auto-sync or manual sync
* Fix - Fixes a bug where 'wclsi_poll' and 'check_for_new_ls_prods' action scheduler jobs show up more than once under the 'pending' section
* Fix - Fixes a bug where imported products with categories are automatically added to 'Uncategorized' (or whatever the default category is)
* Fix - Fixed a bug where imported products (but not on the sync schedule) were still being updated on Lightspeed after a WooCommerce update
* Tweak - Re-arranges selective sync checkbox to display legacy Web Store fields
* Tweak - Removes CSS around hiding selective sync fields

* Fix - Fixes erroneous LS update callbacks that may have been triggered via auto polling and other product update pathways
* Fix - Fixes "PHP Notice: Undefined property: stdClass:httpCode in class-wclsi-init-settings.php" due to token refresh logic
* Tweak - Lowers chances of 429 throttling errors triggered via the "Manual Update via Lightspeed" button for variable products