Fix ruff import order in strands mock model

ruff's `I001` rule groups `temporalio` with other third-party imports
rather than its own block, which broke `poe lint` on CI.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

Author: brianstrauch

tests/strands_plugin/_mock_model.py

@@ -11,11 +11,10 @@
 from collections.abc import AsyncIterable
 from typing import Any
 
+import temporalio.contrib.strands._plugin as _plugin_module
 from strands.models import Model
 from strands.types.streaming import StreamEvent
 
-import temporalio.contrib.strands._plugin as _plugin_module
-
 
 class MockModel(Model):
     def __init__(self, responses: list[str | dict[str, Any]]) -> None: