lock file occupied when generating

[ChenZiHong-Gavin]

Run webui on windows:

Traceback (most recent call last):
  File "D:\miniconda\envs\graphgen\lib\site-packages\gradio\queueing.py", line 667, in process_events
    response = await route_utils.call_process_api(
  File "D:\miniconda\envs\graphgen\lib\site-packages\gradio\route_utils.py", line 349, in call_process_api
    output = await app.get_blocks().process_api(
  File "D:\miniconda\envs\graphgen\lib\site-packages\gradio\blocks.py", line 2274, in process_api
    result = await self.call_function(
  File "D:\miniconda\envs\graphgen\lib\site-packages\gradio\blocks.py", line 1781, in call_function
    prediction = await anyio.to_thread.run_sync(  # type: ignore
  File "D:\miniconda\envs\graphgen\lib\site-packages\anyio\to_thread.py", line 61, in run_sync
    return await get_async_backend().run_sync_in_worker_thread(
  File "D:\miniconda\envs\graphgen\lib\site-packages\anyio\_backends\_asyncio.py", line 2525, in run_sync_in_worker_thread
    return await future
  File "D:\miniconda\envs\graphgen\lib\site-packages\anyio\_backends\_asyncio.py", line 986, in run
    result = context.run(func, *args)
  File "D:\miniconda\envs\graphgen\lib\site-packages\gradio\utils.py", line 915, in wrapper
    response = f(*args, **kwargs)
  File "D:\Project\work\shanghai ai lab\GraphGen\GraphGen\webui\app.py", line 645, in <lambda>
    lambda *args: run_graphgen(
  File "D:\Project\work\shanghai ai lab\GraphGen\GraphGen\webui\app.py", line 218, in run_graphgen
    cleanup_workspace(working_dir)  # Optional: keep for debugging or enable
  File "D:\Project\work\shanghai ai lab\GraphGen\GraphGen\webui\utils\cache.py", line 22, in cleanup_workspace
    shutil.rmtree(folder)
  File "D:\miniconda\envs\graphgen\lib\shutil.py", line 750, in rmtree
    return _rmtree_unsafe(path, onerror)
  File "D:\miniconda\envs\graphgen\lib\shutil.py", line 615, in _rmtree_unsafe
    _rmtree_unsafe(fullname, onerror)
  File "D:\miniconda\envs\graphgen\lib\shutil.py", line 620, in _rmtree_unsafe
    onerror(os.unlink, fullname, sys.exc_info())
  File "D:\miniconda\envs\graphgen\lib\shutil.py", line 618, in _rmtree_unsafe
    os.unlink(fullname)
PermissionError: [WinError 32] 另一个程序正在使用此文件，进程无法访问。: '...\\cache\\58be1a2f-4f9e-4c81-8ab4-3baeb18f6f86\\chunk.db\\LOCK'

[ChenZiHong-Gavin]

Fixed by #162