fix: partial serial no return issue

[rohitwaghchaure]

1st Issue

1. Create Delivery Note for 10 items with serial no

2. Create Return for 1 item with 1 serial no

3. Create another delivery note, qty changes to 9 but the serial numbers auto fetched are all 10.

2nd Issue

Replicated for the document Sales Invoice and Purchase Invoice

1. Make sales invoice for 10 quantity
2. Make sales return for 6 quantity
3. Make one more sales return for remaining quantity, ideally system should show remaining quantity as 4 but it shows the quantity as 10.