fix: check for duplicate pos invoices in closing entry

[ruthra-kumar]

POS Closing entry was accepting duplicate pos invoices. Validation has been added to prevent it.

[codecov]

Codecov Report

Merging #34102 (47add0b) into develop (20bdc63) will decrease coverage by 0.02%.
The diff coverage is 75.00%.

Additional details and impacted files

@@             Coverage Diff             @@
##           develop   #34102      +/-   ##
===========================================
- Coverage    63.88%   63.87%   -0.02%     
===========================================
  Files          817      817              
  Lines        59330    59536     +206     
===========================================
+ Hits         37905    38026     +121     
- Misses       21425    21510      +85     

Impacted Files	Coverage Δ
...ype/pos_invoice_merge_log/pos_invoice_merge_log.py	79.67% <69.23%> (-0.46%)	⬇️
...nts/doctype/pos_closing_entry/pos_closing_entry.py	77.27% <81.81%> (+0.50%)	⬆️
...ock_reposting_settings/stock_reposting_settings.py	29.26% <0.00%> (-4.07%)	⬇️
...egrations/doctype/plaid_settings/plaid_settings.py	46.15% <0.00%> (-2.92%)	⬇️
...ounts/doctype/bank_transaction/bank_transaction.py	67.46% <0.00%> (-2.91%)	⬇️
...nk_reconciliation_tool/bank_reconciliation_tool.py	41.43% <0.00%> (-2.70%)	⬇️
erpnext/accounts/general_ledger.py	94.31% <0.00%> (-0.76%)	⬇️
...rpnext/assets/doctype/asset_repair/asset_repair.py	65.85% <0.00%> (-0.20%)	⬇️
...x_withholding_category/tax_withholding_category.py	85.95% <0.00%> (-0.01%)	⬇️
erpnext/setup/doctype/employee/employee.py	57.76% <0.00%> (ø)
... and 12 more

[ruthra-kumar]

@Mergifyio backport version-14-hotfix version-13-hotfix

[mergify]

backport version-14-hotfix version-13-hotfix

✅ Backports have been created

• #34164 fix: check for duplicate pos invoices in closing entry (backport #34102) has been created for branch version-14-hotfix
• #34165 fix: check for duplicate pos invoices in closing entry (backport #34102) has been created for branch version-13-hotfix