Fix Dockerfile to use gunicorn with Flask app

Dockerfile

@@ -16,6 +16,6 @@ COPY ./src /code/src
 # Create a writable directory for caching/temp files if needed
 RUN mkdir -p /code/temp && chmod 777 /code/temp
 
-# Set the command to run the application
+# Set the command to run the Flask application
 # Note: HF Spaces expects the app to run on port 7860
-CMD ["uvicorn", "src.api.main:app", "--host", "0.0.0.0", "--port", "7860"]
+CMD ["gunicorn", "-b", "0.0.0.0:7860", "src.app:app"]