Add poetry workflow to the contributing guide

[fabianegli]

Add basic poetry usage docuentation and links to the official docs to our developer documentation https://github.com/bigbio/sdrf-pipelines/blob/f7adf1edf3f044f7a3a3ce7957d0bb9459e82bec/CONTRIBUTING.md

[fabianegli]

https://python-poetry.org/docs/basic-usage/