text: Title: Virtual Env is not respected
  Body: Hey, 
  
  I have a dockerfile like this: 
  ...
  FROM tiangolo/uvicorn-gunicorn-fastapi:python3.8 AS service
  COPY --from=test_runner /venv /venv
  ENV PATH=/venv/bin:$PATH
  
  When I run the container It cannot find my installed packaged. 