label-studio-ml-backend's segment_anything_model example bug fix: previous annotation disappearing after making new one

Problem

When I try to use Interactive Annotation in Label Studio with Segment Anything Model Commits version: b2c31d3. I meet a problem, previous annotation is disappeared after making new annotation.(Latest version is fixed this problem[link])

Fix

To fix this problem, we need to modify the label-studio-ml-backend/label_studio_ml/examples/segment_anything_model/segment_anything_model.py file.
change the method to generate result id.

''.join(random.SystemRandom().choice(string.ascii_uppercase + string.ascii_lowercase + string.digits))

to

from uuid import uuid4
str(uuid4())[:4]