Fix missing python dependencies for pagefind

[markcmiller86]

Description

Our CI on develop is currently broken because the step to produce the manual fails due to pagefind changes.

I nelgected to update bv_python.sh to include the new dependencies.

I naively thought that updating requirements.txt was sufficient. And, if we included OpenSSL in our python builds, I think it would be as simple as pip install -r requirements.txt. That is certainly how RTD does our Sphinx builds.

But, not having OpenSSL means we can't rely on pip to download anything and so all of that needs to be taken care of ahead of time in bv_python.sh.

This PR should fix that oversight.

Type of change

• Bug fix~~
• [ ] New feature
• [ ] Documentation update
• [ ] Other

How Has This Been Tested?

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Checklist:

• I have commented my code where applicable.~~
• I have updated the release notes.~~
• I have made corresponding changes to the documentation.~~
• I have added debugging support to my changes.~~
• I have added tests that prove my fix is effective or that my feature works.~~
• I have confirmed new and existing unit tests pass locally with my changes.~~
• I have added new baselines for any new tests to the repo.~~
• I have NOT made any changes to protocol or public interfaces in an RC branch.~~

[biagas]

By itself, this PR might not fix CI. I think the CI container needs to be updated to have the new python modules installed.

[markcmiller86]

@biagas I have tested this locally and with this invokation of build_visit

env PYTHONPATH=pwd/_ext /Users/miller86/visit/visit/test-pagefind-build/third_party/python/3.13.9/arm-apple-darwin24_clang/bin/sphinx-build -E -W --keep-going -b html . _build -a