fix: Shipping Rule picking up old net_rate

[nemesis189]

Problem:

• On applying a shipping rule in an invoice, it was making use of the old net_rate to calculate the charges.
  

Solution:

• Calling the shipping rule calculation method in net total

[codecov]

Codecov Report

Merging #28302 (a8e2c02) into develop (043e325) will increase coverage by 0.00%.
The diff coverage is 100.00%.

❗ Current head a8e2c02 differs from pull request most recent head e7b4204. Consider uploading reports for the commit e7b4204 to get more accurate results

@@           Coverage Diff            @@
##           develop   #28302   +/-   ##
========================================
  Coverage    55.19%   55.20%           
========================================
  Files         1119     1119           
  Lines        66529    66599   +70     
========================================
+ Hits         36722    36764   +42     
- Misses       29807    29835   +28     

Impacted Files	Coverage Δ
erpnext/controllers/taxes_and_totals.py	97.65% <100.00%> (+0.02%)	⬆️
...eport/item_variant_details/item_variant_details.py	31.32% <0.00%> (-53.02%)	⬇️
...work_order_stock_report/work_order_stock_report.py	50.00% <0.00%> (-50.00%)	⬇️
...tch_item_expiry_status/batch_item_expiry_status.py	69.23% <0.00%> (-25.00%)	⬇️
...wise_balance_history/batch_wise_balance_history.py	68.96% <0.00%> (-22.42%)	⬇️
...s/doctype/promotional_scheme/promotional_scheme.py	91.36% <0.00%> (-4.60%)	⬇️
...ctype/woocommerce_settings/woocommerce_settings.py	80.00% <0.00%> (-4.00%)	⬇️
.../hr/doctype/upload_attendance/upload_attendance.py	44.69% <0.00%> (-1.52%)	⬇️
erpnext/stock/report/stock_ageing/stock_ageing.py	89.05% <0.00%> (-1.46%)	⬇️
.../report/stock_projected_qty/stock_projected_qty.py	88.15% <0.00%> (-1.32%)	⬇️
... and 29 more

[nemesis189]

@Mergifyio backport version-13-hotfix version-13-pre-release

[mergify]

backport version-13-hotfix version-13-pre-release

✅ Backports have been created

• #28641 fix: Shipping Rule picking up old net_rate (backport #28302) has been created for branch version-13-hotfix
• #28642 fix: Shipping Rule picking up old net_rate (backport #28302) has been created for branch version-13-pre-release