Fix Dockerfile to use uvicorn for FastAPI endpoints

Dockerfile

@@ -1,5 +1,5 @@
 # SHL Assessment Recommendation Engine
-# HuggingFace Spaces with Gradio UI
+# HuggingFace Spaces with FastAPI + Gradio UI
 
 FROM python:3.10-slim
 
@@ -16,4 +16,4 @@ COPY --chown=user . /app
 
 EXPOSE 7860
 
-CMD ["python", "app.py"]
+CMD ["uvicorn", "app:app", "--host", "0.0.0.0", "--port", "7860"]