BPZ demo data in smoke test

[OliviaLynn]

Bug report Need to add commands to smoke test for getting bpz data from NERSC

Otherwise, the newly moved in bpz notebooks fail:

• 'examples/estimation_examples/BPZ_lite_demo.ipynb'
• 'examples/estimation_examples/BPZ_lite_with_custom_SEDs.ipynb'

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• [x] I have described the situation in which the bug arose, including what code was executed, information about my environment, and any applicable data others will need to reproduce the problem.
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[sschmidt23]

I think the commands are in the notebook, we just have them commented out by default because we didn't like the idea of having a notebook download data files when people just do a run all cells on a demo. We can talk about whether it's ok to just uncomment the lines grabbing the extra files, if it's a blocker for the smoke tests I'd say we just do that.