[docs] [issue30487] DOC: automatically create a venv and install Sphinx when running make

[Caleb Hattingh]

Change by Caleb Hattingh <caleb.hattingh at gmail.com>:


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keywords: +patch
pull_requests: +4303

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Python tracker <report at bugs.python.org>
<https://bugs.python.org/issue30487>
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