fix: not able to cancel purchase receipt for old subcontracting flow

[rohitwaghchaure]

Issue

Traceback (most recent call last):
  File "apps/frappe/frappe/app.py", line 110, in application
    response = frappe.api.handle(request)
               ^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "apps/frappe/frappe/api/__init__.py", line 49, in handle
    data = endpoint(**arguments)
           ^^^^^^^^^^^^^^^^^^^^^
  File "apps/frappe/frappe/api/v1.py", line 36, in handle_rpc_call
    return frappe.handler.handle()
           ^^^^^^^^^^^^^^^^^^^^^^^
  File "apps/frappe/frappe/handler.py", line 49, in handle
    data = execute_cmd(cmd)
           ^^^^^^^^^^^^^^^^
  File "apps/frappe/frappe/handler.py", line 85, in execute_cmd
    return frappe.call(method, **frappe.form_dict)
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "apps/frappe/frappe/__init__.py", line 1697, in call
    return fn(*args, **newargs)
           ^^^^^^^^^^^^^^^^^^^^
  File "apps/frappe/frappe/utils/typing_validations.py", line 31, in wrapper
    return func(*args, **kwargs)
           ^^^^^^^^^^^^^^^^^^^^^
  File "apps/frappe/frappe/desk/form/save.py", line 57, in cancel
    doc.cancel()
  File "apps/frappe/frappe/utils/typing_validations.py", line 31, in wrapper
    return func(*args, **kwargs)
           ^^^^^^^^^^^^^^^^^^^^^
  File "apps/frappe/frappe/model/document.py", line 1046, in cancel
    return self._cancel()
           ^^^^^^^^^^^^^^
  File "apps/frappe/frappe/model/document.py", line 1029, in _cancel
    return self.save()
           ^^^^^^^^^^^
  File "apps/frappe/frappe/model/document.py", line 331, in save
    return self._save(*args, **kwargs)
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "apps/frappe/frappe/model/document.py", line 384, in _save
    self.run_post_save_methods()
  File "apps/frappe/frappe/model/document.py", line 1126, in run_post_save_methods
    self.run_method("on_cancel")
  File "apps/frappe/frappe/model/document.py", line 955, in run_method
    out = Document.hook(fn)(self, *args, **kwargs)
          ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "apps/frappe/frappe/model/document.py", line 1315, in composer
    return composed(self, method, *args, **kwargs)
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "apps/frappe/frappe/model/document.py", line 1297, in runner
    add_to_return_value(self, fn(self, *args, **kwargs))
                              ^^^^^^^^^^^^^^^^^^^^^^^^^
  File "apps/frappe/frappe/model/document.py", line 952, in fn
    return method_object(*args, **kwargs)
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "apps/erpnext/erpnext/stock/doctype/purchase_receipt/purchase_receipt.py", line 410, in on_cancel
    self.update_stock_ledger()
  File "apps/erpnext/erpnext/controllers/buying_controller.py", line 562, in update_stock_ledger
    if (self.is_subcontracted and (d.bom or d.fg_item)) or d.from_warehouse
                                            ^^^^^^^^^
AttributeError: 'PurchaseReceiptItem' object has no attribute 'fg_item'