fix: include field add_deduct_tax in Purchase Taxes setup

[barredterra]

Issue

> bench migrate

  File "/home/frappe/frappe-bench/apps/erpnext/erpnext/setup/doctype/company/company.py", line 114, in on_update
    self.create_default_tax_template()
  File "/home/frappe/frappe-bench/apps/erpnext/erpnext/setup/doctype/company/company.py", line 72, in create_default_tax_template
    setup_taxes_and_charges(self.name, self.country)
  File "/home/frappe/frappe-bench/apps/erpnext/erpnext/setup/setup_wizard/operations/taxes_setup.py", line 26, in setup_taxes_and_charges
    from_detailed_data(company_name, country_wise_tax.get('chart_of_accounts'))
  File "/home/frappe/frappe-bench/apps/erpnext/erpnext/setup/setup_wizard/operations/taxes_setup.py", line 88, in from_detailed_data
    make_taxes_and_charges_template(company_name, 'Purchase Taxes and Charges Template', template)
  File "/home/frappe/frappe-bench/apps/erpnext/erpnext/setup/setup_wizard/operations/taxes_setup.py", line 121, in make_taxes_and_charges_template
    return frappe.get_doc(template).insert(ignore_permissions=True)
  File "/home/frappe/frappe-bench/apps/frappe/frappe/model/document.py", line 238, in insert
    self._validate()
  File "/home/frappe/frappe-bench/apps/frappe/frappe/model/document.py", line 492, in _validate
    self._validate_mandatory()
  File "/home/frappe/frappe-bench/apps/frappe/frappe/model/document.py", line 811, in _validate_mandatory
    name=self.name))
frappe.exceptions.MandatoryError: [Purchase Taxes and Charges Template, Abziehbare Vorsteuer 19% - AVE]: add_deduct_tax

Note: the after_install hook of my custom app creates a new Company. This is why I can trigger this error via bench migrate. You should be able to reproduce it by creating a new Company programatically.

Solution

Include the field add_deduct_tax as a default in taxes_setup.py. For some reason the field's default value is apparently not used in this case.

[barredterra]

Any ideas how to fix the failing tests? They don't seem to be related to this PR.