Fix: use CUDA base image for GPU support

Dockerfile

@@ -1,8 +1,9 @@
-FROM python:3.10-slim
+FROM nvidia/cuda:12.1.0-runtime-ubuntu22.04
 
 WORKDIR /app
 
-# HF Spaces runs as uid 1000 - set all cache dirs to writable locations
+RUN apt-get update && apt-get install -y python3 python3-pip && rm -rf /var/lib/apt/lists/*
+
 ENV HF_HOME=/tmp/hf_cache
 ENV TRANSFORMERS_CACHE=/tmp/hf_cache
 ENV TORCH_HOME=/tmp/torch_cache
@@ -14,7 +15,7 @@ ENV USER=user
 RUN mkdir -p /tmp/hf_cache /tmp/torch_cache /tmp/cache /tmp/home && \
     chmod -R 777 /tmp/hf_cache /tmp/torch_cache /tmp/cache /tmp/home
 
-RUN pip install --no-cache-dir \
+RUN pip3 install --no-cache-dir \
     torch \
     transformers \
     trl \
@@ -26,4 +27,5 @@ RUN pip install --no-cache-dir \
 COPY train_on_hf.py .
 RUN chmod -R 777 /app
 
-CMD ["sh", "-c", "python train_on_hf.py --hf-token $HF_TOKEN"]
+EXPOSE 7860
+CMD ["sh", "-c", "python3 train_on_hf.py --hf-token $HF_TOKEN"]