Update test_formatters.py

Bad cell ref [0, 2] -> [0, 3]

Author: vinraspa

tests/test_formatters.py

@@ -56,7 +56,7 @@ def test_writing_date_format(self):
         assert r[0, 1].strftime("%H:%M:%S") == "11:11:11"
         assert isinstance(r[0, 2], datetime.date) is True
         assert r[0, 2].strftime("%d/%m/%y %H:%M:%S") == "25/12/14 11:11:11"
-        assert isinstance(r[0, 2], datetime.timedelta)
+        assert isinstance(r[0, 3], datetime.timedelta)
         assert r[0, 1].strftime("%H:%M:%S") == "3:30:20"
         os.unlink(excel_filename)