chore: remove all six compat code

erpnext/controllers/tests/test_item_variant.py

@@ -1,9 +1,7 @@
-
 import json
 import unittest
 
 import frappe
-from six import string_types
 
 from erpnext.controllers.item_variant import copy_attributes_to_variant, make_variant_item_code
 from erpnext.stock.doctype.item.test_item import set_item_variant_settings
@@ -20,7 +18,7 @@ class TestItemVariant(unittest.TestCase):
 		self.assertEqual(variant.get("quality_inspection_template"), "_Test QC Template")
 
 def create_variant_with_tables(item, args):
-	if isinstance(args, string_types):
+	if isinstance(args, str):
 		args = json.loads(args)
 
 	qc_name = make_quality_inspection_template()