fix: better permission check for viewing pending vouchers

[vorasmit]

https://discuss.frappe.io/t/gst-setting-write-access-for-gst-balance-report/131260

This ensures that someone with read permissions will still be able to update the docs with Company GSTIN with appropriate doc permissions.

This can finally be then executed by someone with write permissions for the doc.

_{Huly®: IC-2651}

[codecov]

Codecov Report

Attention: Patch coverage is 0% with 1 line in your changes missing coverage. Please review.

Project coverage is 60.26%. Comparing base (48572d2) to head (bfc383c).
Report is 18 commits behind head on develop.

Files	Patch %	Lines
...liance/gst_india/report/gst_balance/gst_balance.py	0.00%	1 Missing ⚠️

Additional details and impacted files

@@           Coverage Diff            @@
##           develop    #2528   +/-   ##
========================================
  Coverage    60.26%   60.26%           
========================================
  Files          119      119           
  Lines        11394    11394           
========================================
  Hits          6867     6867           
  Misses        4527     4527           

Files	Coverage Δ
...liance/gst_india/report/gst_balance/gst_balance.py	0.00% <0.00%> (ø)