gh-69619: Clarify whitespace definition in str.strip docs

[Daniil20xx]

Clarify that whitespace characters in str.strip are defined by Unicode,
including spaces, tabs, and newline characters.

• Issue: whitespace in strip()/lstrip()/rstrip() #69619

[python-cla-bot]

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[read-the-docs-community]

Documentation build overview

📚 cpython-previews | 🛠️ Build #32745644 | 📁 Comparing ace5bd1 against main (6d5be4b)

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2 files changed

± library/stdtypes.html
± whatsnew/changelog.html

[StanFromIreland]

This is inaccurate, the UCD defines properties, not such categories. For example, the file separator is not covered by your sentence:

>>> '\x1c'.isspace()
True
>>> '\x1c'.strip()
''

I think it would be simpler to link to str.isspace(), which already lists all the properties precisely.

[miss-islington-app]

Thanks @Daniil20xx for the PR, and @encukou for merging it 🌮🎉.. I'm working now to backport this PR to: 3.14.
🐍🍒⛏🤖

[miss-islington-app]

Thanks @Daniil20xx for the PR, and @encukou for merging it 🌮🎉.. I'm working now to backport this PR to: 3.13.
🐍🍒⛏🤖

[miss-islington-app]

Thanks @Daniil20xx for the PR, and @encukou for merging it 🌮🎉.. I'm working now to backport this PR to: 3.15.
🐍🍒⛏🤖

[encukou]

Thank you!

[bedevere-app]

GH-150047 is a backport of this pull request to the 3.13 branch.

[bedevere-app]

GH-150048 is a backport of this pull request to the 3.14 branch.

[bedevere-app]

GH-150049 is a backport of this pull request to the 3.15 branch.