sklearn requirement breaks openai[embeddings] install

when installing the `openai[embeddings]` requirement, both `sklearn` and `scikit-learn` are listed as requirements [source](https://github.com/openai/openai-python/blob/main/setup.cfg#L48).



 However, `sklearn` is deprecated, and is causing `pip install openai[embeddings]` to fail. See the following output from my CI build:



```

Collecting sklearn

  Downloading sklearn-0.0.post1.tar.gz (3.6 kB)

  Preparing metadata (setup.py): started

  Preparing metadata (setup.py): finished with status 'error'

  error: subprocess-exited-with-error

  

  × python setup.py egg_info did not run successfully.

  │ exit code: 1

  ╰─> [18 lines of output]

      The 'sklearn' PyPI package is deprecated, use 'scikit-learn'

      rather than 'sklearn' for pip commands.

      

      Here is how to fix this error in the main use cases:

      - use 'pip install scikit-learn' rather than 'pip install sklearn'

      - replace 'sklearn' by 'scikit-learn' in your pip requirements files

        (requirements.txt, setup.py, setup.cfg, Pipfile, etc ...)

      - if the 'sklearn' package is used by one of your dependencies,

        it would be great if you take some time to track which package uses

        'sklearn' instead of 'scikit-learn' and report it to their issue tracker

      - as a last resort, set the environment variable

        SKLEARN_ALLOW_DEPRECATED_SKLEARN_PACKAGE_INSTALL=True to avoid this error

      

      More information is available at

      https://github.com/scikit-learn/sklearn-pypi-package

      

      If the previous advice does not cover your use case, feel free to report it at

      https://github.com/scikit-learn/sklearn-pypi-package/issues/new

      [end of output]

  

  note: This error originates from a subprocess, and is likely not a problem with pip.

error: metadata-generation-failed



× Encountered error while generating package metadata.

╰─> See above for output.

```



A simple fix would be to simply remove `sklearn` from the list of dependencies of `openai[embeddings]`.



I can open a PR for this if necessary.

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