I use the AWS Lambda docker image to develop and do some test on my local host or during CI/CD.
On my Docker file I added `ENV PYTHONPATH "${PYTHONPATH}:/var/task"` to bind `/var/task` where my python libraries are installed.

I would to do the same but without add `ENV PYTHONPATH "${PYTHONPATH}:/var/task"` in my Dockerfile.

I tried to add this line in my docker-compose but my python path wasn't updated.

```
    environment:
      - PYTHONPATH="${PYTHONPATH}:/var/task"

```

What did I do wrong?