fix(lint): reorder imports per PEP 8 ruff/isort rule in actor_loading_steps.py

The typing.cast import was placed after third-party imports (behave),
violating ruff/isort PEP 8 ordering enforced by CI lint. Move it into
the stdlib block before the blank-line separator from third-party.

Fixes CI / lint failure on this branch. Closes #8588

features/steps/actor_loading_steps.py

@@ -6,10 +6,10 @@ import tempfile
 import threading
 import time
 from pathlib import Path
+from typing import cast
 
 from behave import given, then, when
 from behave.runner import Context
-from typing import cast
 
 from cleveragents.actor.loader import ActorLoader
 from cleveragents.actor.schema import ActorConfigSchema