deps/segment_anything: Add small model

In its current form, segment_anything.json only downloads the checkpoint for the large vit_h model of segment-anything. However, the small vit_b model is required for runtime sensitive tasks like segmentation on ARMAR-DE with the contaminated_segment_anything package.

Currently, a manual download of the model checkpoint for the vit_b model is required when using contaminated_segment_anything. The changes of this merge request aim at resolving the manual download of the vit_b model checkpoint by adding it to the downloaded model checkpoints when installing the segment-anything dependency via axii.