Added this because recently, there have been more problems with `docker-compose build` where it errors:
ERROR: Service 'server' failed to build: failed to parse platform : "" is an invalid component of "": platform specifier component must match "^[A-Za-z0-9_-]+$": invalid argument
Recent Docker versions have switched to using `buildx` (BuildKit) to build containers, but that needs to be enabled, either in `daemon.json` or through an environment variable. But since we are using Docker Compose, it doesn't pass it to Docker; so the environment variable needs to be set. At least that's what I've heard and figured out sweat_smile My explanation might be very wrong - but it works :)
