TODO: Re-add ocbpy & pysat to notebooks

[sapols]

In this commit I temporarily removed:

• pysat from unit-tests.ipynb
• pysat and ocbpy from import-test.ipynb

because pysat is unable to import inside the JupyterHub we're standing up for ML-Helio. (The issue was caused by NFS not supporting the file locking mechanisms that pysat (a dependency of ocbpy) requires during import.)

Re-add them after ML-Helio.

[sapols]

Re-added in this commit