[FIX] product_cost_usd: order in recompute purchase price

The `sale_stock_margin` module recomputes the purchase price in sale
order lines and calls `super()` only over the lines without a stock
move related to it. This causes this module to not recompute the lines
with stock moves related, leading to incorrect computation of the
purchase price.

This commit adds the `sale_stock_margin` module as a dependency in
order to first run this module compute.

product_cost_usd/__manifest__.py

@@ -10,6 +10,7 @@
     "license": "LGPL-3",
     "depends": [
         "sale_margin",
+        "sale_stock_margin",
     ],
     "demo": [
         "demo/product_pricelist_demo.xml",