Explore feasibility of github actions to test the notebooks

[antonum]

Explore the possibility of automatically testing the notebooks.

/~https://github.com/treebeardtech/nbmake

The following command line sequence works locally for some notebooks and fails for othes, but can be a promising avenue to explore:

python3 -m venv venv
source venv/bin/activate
pip install pytest nbmake
export OPENAI_API_KEY="sk-xxxxxxxxx-add-your-openai-api-key-here-xxxxxxxx"
pytest --nbmake **/*ipynb

Plain Redis notebooks (00-03), pass the tests while connecting to the laptop-local redis. OpenAI fails with either getpass if no OPENAI_API_KEY is defined or IndexError: list index out of range.

Dolly-based notebooks timeout (exclude from tests or increase timeout) - executing Dolly on CPU is expected to take an extra long time.