Stock sync does not take into account reserved quantity

[FreezeS]

How to reproduce (tested on erpnext 13.4.1, woocommerceconnector 1.6.0):

• WooCommerce Config with Sync Item QTY enabled, trigger to update item stock disabled:
• make an item and set it to sync stock with WooCommerce
• make a Purchase order and Purchase receipt for, let's say 30 pcs
• sync with WooCommerce - item should show 30 pcs
• make an order for 29 pcs - stock should show 1 pcs on WC
• sync
• will get a Sales Order in erpNext for 29 pcs
• go to the item, check Stock Levels - should show 29 reserved - 30 Actual Qty
• make a new Purchase order and Purchase receipt for 50 pcs
• sync
• check the item stock levels: 29 reserved - 80 actual
• check stock levels on WooCommerce: 80 pcs instead of 51 pcs
• now a customer can place an order for 80 pcs and you have 2 sales order, one 29 pcs and one 80 pcs but Purchase receipts for only 80 pcs.