fix: '0' rate LDC's Invoice net totals should be ignored (backport #45639)

[mergify]

| Dec 2024 | Jan 2025 |
|          |          |
| LDC @ 0% |          |
|----------+----------|
| pinv1    | pinv3    |
| pinv2    |          |

Consider above scenario, LDC of '0' rate active for December 2024 and thera are purchase invoices booked in that period. Now, when a purchase invoice is created outside LDC, system incorrectly considers net total of pinv1 and pinv2 on TDS calculation as there are no taxes on the previous entries.

todo:

• test case

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This is an automatic backport of pull request #45639 done by [Mergify](https://mergify.com).

[mergify]

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	both modified:   erpnext/accounts/doctype/tax_withholding_category/test_tax_withholding_category.py

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