fix race condition in result.info access

result.info is a property that re-fetches from the backend on each
access. Snapshot it into a local variable to prevent the value changing
between the isinstance check and the .get() call.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

Author: snopoke

taskbadger/celery.py

@@ -131,7 +131,8 @@ def apply_async(self, *args, **kwargs):
 
         result = super().apply_async(*args, **kwargs)
 
-        tb_task_id = result.info.get(TB_TASK_ID) if isinstance(result.info, dict) else None
+        info = result.info
+        tb_task_id = info.get(TB_TASK_ID) if isinstance(info, dict) else None
         setattr(result, TB_TASK_ID, tb_task_id)
 
         _get_task = functools.partial(get_task, tb_task_id) if tb_task_id else lambda: None