fix: adjusted incoming rate for zero rated item in purchase receipt (backport #44415)

[mergify]

The incoming rate is not adjusted when the Item rate is 0 in the Purchase Receipt.

Steps To Replicate:
To replicate the issue:

• In Buying Settings, enable Set Landed Cost Based on Purchase Invoice Rate (you have to disable Maintain Same Rate Throughout the Purchase Cycle first)
• Create a Purchase Receipt with a 0 rate in Item.
• Create a Purchase Invoice for the same receipt with some rate now
• Check the value in Stock Balance and Trial Balance

Frappe Support Issue: https://support.frappe.io/app/hd-ticket/25152

backport version-15
backport version-14

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This is an automatic backport of pull request #44415 done by [Mergify](https://mergify.com).