test: clear tax rules before making POS Invoices (#25171)

diff --git a/erpnext/accounts/doctype/pos_invoice/test_pos_invoice.py b/erpnext/accounts/doctype/pos_invoice/test_pos_invoice.py
index 054afe5..6d388c4 100644
--- a/erpnext/accounts/doctype/pos_invoice/test_pos_invoice.py
+++ b/erpnext/accounts/doctype/pos_invoice/test_pos_invoice.py
@@ -12,6 +12,10 @@
 from erpnext.stock.doctype.item.test_item import make_item
 
 class TestPOSInvoice(unittest.TestCase):
+	@classmethod
+	def setUpClass(cls):
+		frappe.db.sql("delete from `tabTax Rule`")
+
 	def tearDown(self):
 		if frappe.session.user != "Administrator":
 			frappe.set_user("Administrator")