Fix lint issues in asyncio_utils.py

- Remove trailing whitespace from blank lines
- Remove unused loop variable

Co-Authored-By: João <joao@crewai.com>

src/crewai/utilities/asyncio_utils.py

@@ -1,7 +1,8 @@
 """Utilities for handling asyncio operations safely across different contexts."""
 
 import asyncio
-from typing import Any, Coroutine
+from collections.abc import Coroutine
+from typing import Any
 
 
 def run_coroutine_sync(coro: Coroutine) -> Any:
@@ -22,11 +23,10 @@ def run_coroutine_sync(coro: Coroutine) -> Any:
         Any exception raised by the coroutine
     """
     try:
-        loop = asyncio.get_running_loop()
+        asyncio.get_running_loop()
     except RuntimeError:
         return asyncio.run(coro)
     else:
-        import concurrent.futures
         import threading
 
         result = None