Expand `shell` environment variables in docker compose

[zhukovdm]

The construction below injects environment variables into a container. However, these variables are not visible in the file, and ${VAR} ends up being undefined. The true value of this particular variable is defined in the ./infra/.env file, while variables for other services are defined in the compose file.

services:
  routing:
    environment:
      - REGION_FILE=...
    entrypoint: ...${REGION_FILE}...