Fix type hint in test_server_side_scripting for Python < 3.9

unittests/test_server_side_scripting.py

@@ -28,8 +28,9 @@ from unittest.mock import Mock
 from linkahead.utils import server_side_scripting as sss
 from linkahead.connection.mockup import MockUpServerConnection, MockUpResponse
 from linkahead import configure_connection
+from typing import List
 
-_REMOVE_FILES_AFTERWARDS: list[str] = []
+_REMOVE_FILES_AFTERWARDS: List[str] = []
 
 
 def setup_module():