Decrease CI network failures

[dolfim-ibm]

Problem description

Currently, almost any CI build fails with timeouts downloading the model weights from HF.
This happens since a few weeks and doesn't seem to improve.

This fails in two ways:

• When downloading the weights
• When checking if a new version of the models should be fetched

Proposed solution 1

Download the weights once and use them in the whole CI build with artifacts_path.

Proposed solution 2

Use GH cache to keep the model weights locally. This doesn't require any change in the usage.