fix: Use anyio for file operations in a few places (#5167)

Use anyio for file operations in a few places

src/backend/tests/unit/api/v1/test_files.py

@@ -7,6 +7,7 @@ from io import BytesIO
 from pathlib import Path
 from unittest.mock import MagicMock
 
+import anyio
 import pytest
 from asgi_lifespan import LifespanManager
 from httpx import ASGITransport, AsyncClient
@@ -76,7 +77,7 @@ async def files_client_fixture(
         monkeypatch.undo()
         # clear the temp db
         with suppress(FileNotFoundError):
-            db_path.unlink()
+            await anyio.Path(db_path).unlink()
 
 
 @pytest.fixture