Fix docker compose validation error

[spaceo]

Make shure we have unique yaml keys.
Inspired by this post:
docker/compose#10411 (comment)

[kasperg]

👍 LGTM

I expect this is referred to errors seen in e.g. #299.

Since the problems originate in the setup provided by Lagoon you could consider also mentioning the problem and potentially providing a fix in there: https://github.com/lagoon-examples/drupal9-base/blob/main/docker-compose.yml.

In general I do not like problems such as this occurring unrelated to our code changes. I cannot see how we could do anything different here. As I understand it a fixed ubuntu-22.04 runner would suffer from the same problem.