Fix: install PyTorch with CUDA 12.1 support

Dockerfile

@@ -11,12 +11,15 @@ ENV TORCHINDUCTOR_CACHE_DIR=/tmp/torch_cache
 ENV XDG_CACHE_HOME=/tmp/cache
 ENV HOME=/tmp/home
 ENV USER=user
+ENV PYTHONUNBUFFERED=1
 
 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
 
+# Install PyTorch with CUDA 12.1 support explicitly
+RUN pip3 install --no-cache-dir torch --index-url https://download.pytorch.org/whl/cu121
+
 RUN pip3 install --no-cache-dir \
-    torch \
     transformers \
     trl \
     peft \