FIX: Production Plan -> Stock Qty from SO Item instead of Qty

[MaxMorais]

When building a production plan from a Sales Order, by default ERPNext take into account the so_item.qty field, this covers 90% of the good scenarios, but, if an Item have an different selling uom, it will raise an issue on manufacturing.

For instance, let's consider an Ice Cream factory!

For Ice Cream, the Stock Unit is Mililitre

The Standard Selling Unit is 1 Litre Package

So, let's consider a Sales of 2000 Litres

On the Sales Order Item, ERPNext calculate properly the expected Stock Qty 2.000.000 Mililitres

But, when fetching the Sales Order on the Production Plan we have

So all the Raw Materials get wrong

But with a manual fix

We get the right raw materials

Prooving that ERPNext is fetching the wrong value