Stable Diffusion Dockerfile for ROCm

Run Stable Diffusion on an AMD card, using this method. Tested on my RX 6900 XT.

1. Obtain sd-v1-4.ckpt and put it in models/.
2. Run ./build-rocm to build the Docker image.
3. Run ./run-rocm to run a shell in the Docker container.
4. Inside the container, you can do e.g. python scripts/txt2img.py --outdir /output --plms --seed $RANDOM$RANDOM --prompt "a unicorn riding a purple tricycle".