fix: update PermissionHandler import path in transform test

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

Author: SteveSandersonMS

python/e2e/test_system_message_transform.py

@@ -6,7 +6,7 @@
 
 import pytest
 
-from copilot import PermissionHandler
+from copilot.session import PermissionHandler
 
 from .testharness import E2ETestContext
 from .testharness.helper import write_file