[demo] add GPU to resources (facebookresearch#355)

This small PR adds GPU specification in `docker-compose.yaml` for the SAM 2 interactive webdemo, following https://docs.docker.com/compose/how-tos/gpu-support/#example-of-a-compose-file-for-running-a-service-with-access-to-1-gpu-device. It fixes a GPU access error as reported in facebookresearch#354.

(close facebookresearch#354)

docker-compose.yaml

@@ -33,18 +33,10 @@ services:
       - VIDEO_ENCODE_MAX_WIDTH=1280
       - VIDEO_ENCODE_MAX_HEIGHT=720
       - VIDEO_ENCODE_VERBOSE=False
-      # Optional: This ensures the container is using the GPU
-      - NVIDIA_VISIBLE_DEVICES=all
-      - NVIDIA_DRIVER_CAPABILITIES=compute,utility
-      - MAX_UPLOAD_VIDEO_DURATION=600
-      - VIDEO_ENCODE_VERBOSE=True
-
-
-    # Uncomment this section to enable GPU support via NVIDIA Container Toolkit
     deploy:
       resources:
         reservations:
           devices:
             - driver: nvidia
-              count: all
+              count: 1
               capabilities: [gpu]