Test docs

[sneakers-the-rat]

Fix: #71

To keep the documentation from being broken, let's test the docs - this action builds the docs and raises warnings as errors.

Error from documenting the CLI seems to have come from needing to have matplotlib installed to import anything, which shouldn't be the case - we want matplotlib to be optional bc it's heavy. So i changed that importerror to a check when one attempts to use the streamplotter instead

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📚 Documentation preview 📚: https://miniscope-io--75.org.readthedocs.build/en/75/

[coveralls]

coverage: 77.18% (-0.04%) from 77.22%
when pulling bb77216 on docs-tests
into 87487a1 on main.

[t-sasatani]

Looks like this can't break anything. Also, it's technically tested in the experiment-YYYYMMDD branch, so I think it's good.