set conditional execution on python >= 3.9 on backup tests

Author: bckohan

django_typer/tests/test_backup_example.py

@@ -1,4 +1,6 @@
 import os
+import sys
+import pytest
 
 from django.test import SimpleTestCase
 from pathlib import Path
@@ -9,6 +11,7 @@
 BACKUP_DIRECTORY = Path(__file__).parent / "_test_archive"
 
 
+@pytest.mark.skipif(sys.version_info < (3, 9), reason="requires python3.9 or higher")
 class TestBackupExample(SimpleTestCase):
     databases = {"default"}