fixed async call issue

tests/test_sandbox.py

@@ -1,3 +1,4 @@
+import asyncio
 from unittest.mock import AsyncMock, MagicMock, patch
 
 import pytest
@@ -137,7 +138,7 @@ async def test_real_sandbox_starts():
         assert sb.container is not None
 
         # Verify container is actually running
-        result = await sb.run("echo 'sandbox started'")
+        result = await asyncio.to_thread(sb.run, "echo 'sandbox started'")
         assert "sandbox started" in result