Update pip usage example with CS9

[jcapiitao]

CS8 is EOL since May 31 2024 [1], this patch updates the example of pip usage to use CS9.
Plus, we need to enable the CRB repository which provides gobject-introspection-devel.

[1] https://blog.centos.org/2023/04/end-dates-are-coming-for-centos-stream-8-and-centos-linux-7/

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• Code coverage from testing does not decrease and new code is covered
• Docs updated (if applicable)
• Docs links in the code are still valid (if docs were updated)

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[eskultety]

Disclaimer: I didn't know we had an example like this until you pointed it out.

CS is a rolling distro which breaks package updates more often than not sadly (at least it used to be the case). I mean what you have here is all fine but strictly from docs POV I just wonder if it deserves the promotion (even just as an example) since it requires the Content Ready Builder repo to enable headers. Anyway, I think this hunk would be slightly simplified if you replaced CS with an example using AlmaLinux or Rocky where you don't need either the config manager or the CRB repo.

[brunoapimentel]

Atomic reactor uses Fedora, so we might as well just do the same.

[eskultety]

Works too.