[Python][CI] python-sdist job should publish sdist as artifact

[pitrou]

Describe the enhancement requested

When running the python-sdist job it would be nice to access the sdist after the job has finished, for example to manually check its contents.

Component(s)

Continuous Integration, Python

[pitrou]

@raulcd @AlenkaF

[raulcd]

Issue resolved by pull request 49008
#49008