Add gunicorn to get rid of warnings

Dockerfile

@@ -9,7 +9,6 @@ COPY . .
 RUN mkdir -p /data
 
 ENV DATABASE_PATH=/data/inventory.db
-ENV FLASK_APP=app.py
 
 EXPOSE 5000
-CMD ["python", "app.py"]
+CMD ["gunicorn", "--bind", "0.0.0.0:5000", "--workers", "2", "--access-logfile", "-", "app:app"]

requirements.txt

@@ -1 +1,2 @@
 Flask==3.1.1
+gunicorn==23.0.0