DRAFT. Expand test for geoscience libraries

[eshntmshra]

Deepens the tests for four geophysics libraries from import/version-only checks to a real operation that exercises the package's core functionality:

• dascore — load an example DAS patch and decimate it
• obspy — read the bundled example waveform and apply a bandpass filter
• obsplus — index a directory with a WaveBank and confirm the channels round-trip
• pygmt — render a coastline (also exercises the apt-installed GMT map data, gmt-gshhg / gmt-dcw, which nothing tested before)

All tests use bundled or synthetic data that require no network, no credentials, no external files.

Ran pytest test_packages.py -v and re-ran the test_notebook.ipynb notebook cells in GeoLab and all tests passed.

[sarahw-earthscope]

This looks good to me!
We need to ensure the developer checklist includes instructions to update these test files with any new packages they add.

[sarahw-earthscope]

Not a comment on the test package... but we need to consider why we are including dascore in the image build at all. We don't currently provide das data through our archive, and I'm not sure we want to encourage researchers to upload das data (big files) to geolab for the sole purpose of processing it.