install sam2 the way facebook says

vr180_matting/main.py

@@ -111,6 +111,8 @@ matting:
   use_disparity_mapping: true
   memory_offload: true
   fp16: true
+  sam2_model_cfg: "sam2.1_hiera_l"
+  sam2_checkpoint: "segment-anything-2/checkpoints/sam2.1_hiera_large.pt"
   
 output:
   path: "path/to/output/"