Update `test` dependency from `nteract-scrapbook` to `scrapbook`

[matthewfeickert]

Summary

Running the notebook tests generates the warning

warnings.warn("'nteract-scrapbook' package has been renamed to `scrapbook`. No new releases are going out for this old package name.", FutureWarning)

as nteract-scrapbook is now scrapbook. All that needs to be done is to change the name used in steup.py for the test extra:

https://github.com/scikit-hep/pyhf/blob/29bc6daed55b40711fabd9b22d3e76f9ee15657d/setup.py#L42

Additional Information

No response

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