[documentation] documentation built by gitlab pipeline is missing images, whereas readthedocs does have them

In !599 (merged) I noticed a difference in the documentation that is built by the gitlab pipeline compared to the one built externally on readthedocs.

In the user guide for example we have the one generated by the pipeline:

vs the one generated by readthedocs

This is inconvenient and should be looked into.

link to pipeline generated docs: https://quantify-os.gitlab.io/-/quantify-scheduler/-/jobs/3784345308/artifacts/docs/_build/html/user_guide.html

link to readthedocs generated docs: https://quantify-quantify-scheduler--599.com.readthedocs.build/en/599/user_guide.html

It's probably a mismatch of package versions.