fix: webscaper sometime not work

[hjlarry]

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Summary

fix #35449

the readabilipy always try to use nodejs to parse the html which will cause this error. more about this https://github.com/alan-turing-institute/ReadabiliPy

try to mock the error:

Traceback (most recent call last):
  File "<stdin>", line 2, in <module>
  File "/Users/hejl/projects/dify/api/.venv/lib/python3.12/site-packages/readabilipy/simple_json.py", line 41, in simple_json_from_html_string
    if use_readability and not have_node():
                               ^^^^^^^^^^^
  File "/Users/hejl/projects/dify/api/.venv/lib/python3.12/site-packages/readabilipy/simple_json.py", line 36, in have_node
    run_npm_install()
  File "/Users/hejl/projects/dify/api/.venv/lib/python3.12/site-packages/readabilipy/utils.py", line 60, in run_npm_install
    cp = subprocess.run(["npm", "install"], check=True)
         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/Users/hejl/.local/share/uv/python/cpython-3.12.12-macos-aarch64-none/lib/python3.12/subprocess.py", line 571, in run
    raise CalledProcessError(retcode, process.args,
subprocess.CalledProcessError: Command '['npm', 'install']' returned non-zero exit status 1.

Screenshots

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Checklist

• This change requires a documentation update, included: Dify Document
• I understand that this PR may be closed in case there was no previous discussion or issues. (This doesn't apply to typos!)
• I've added a test for each change that was introduced, and I tried as much as possible to make a single atomic change.
• I've updated the documentation accordingly.
• I ran make lint && make type-check (backend) and cd web && pnpm exec vp staged (frontend) to appease the lint gods