fix: purchase invoice return GLe

voucher_wise_stock_value contains tuples and the condition was looking
for string, so it's never triggered.

Caused by https://github.com/frappe/erpnext/pull/24200

erpnext/stock/tests/test_utils.py

@@ -38,6 +38,23 @@ class StockTestMixin:
 
 				self.assertEqual(v, act_value, msg=f"{k} doesn't match \n{exp_sle}\n{act_sle}")
 
+	def assertGLEs(self, doc, expected_gles, gle_filters=None, order_by=None):
+		filters = {"voucher_no": doc.name, "voucher_type": doc.doctype, "is_cancelled": 0}
+
+		if gle_filters:
+			filters.update(gle_filters)
+		actual_gles = frappe.get_all(
+			"GL Entry",
+			fields=["*"],
+			filters=filters,
+			order_by=order_by or "posting_date, creation",
+		)
+
+		for exp_gle, act_gle in zip(expected_gles, actual_gles):
+			for k, exp_value in exp_gle.items():
+				act_value = act_gle[k]
+				self.assertEqual(exp_value, act_value, msg=f"{k} doesn't match \n{exp_gle}\n{act_gle}")
+
 
 class TestStockUtilities(FrappeTestCase, StockTestMixin):
 	def test_barcode_scanning(self):