fix: make SAM 2 work in case data value is a list of images

[alessandro-oe]

Currently SAM 2 doesn't work when the label studio interface image is defined with valueList

it gets this error:

  File "/app/model.py", line 86, in _sam_predict
    self.set_image(img_url, task.get('id'))
  File "/app/model.py", line 80, in set_image
    image_path = get_local_path(image_url, task_id=task_id)
                 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/opt/conda/lib/python3.11/site-packages/label_studio_sdk/_extensions/label_studio_tools/core/utils/io.py", line 114, in get_local_path
    if url.startswith("upload") or url.startswith("/upload"):
       ^^^^^^^^^^^^^^
AttributeError: 'list' object has no attribute 'startswith'

This PR considers this case and adds a fix