feat: Adding support for older compose versions

[Gordonby]

Description

This adds legacy docker-compose support through a compose-version flag.
This then alters the generation of the compose.yaml to fit a legacy structure

I don't expect this to be a very popular PR, and I'm probably expecting more dialog than anything else. If it is seen to be worthy and merged then that is a bonus.

I am also still in the midst of testing other properties and scenarios against my new local version of score-compose so will raise this as draft.

Example output difference

What does this PR do?

I have a restricted development environment which uses podman and has support for older versions of docker compose.
When I use score-compose against my score file it complains that various parts of the file are not supported.
These changes facilitate a compatible compose file that does up.

Types of changes

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to change)
• New chore (expected functionality to be implemented)

Checklist:

• My change requires a change to the documentation.
  • I have updated the documentation accordingly.
• I've signed off with an email address that matches the commit author.

[mathieu-benoit]

Hi @Gordonby, thank you for proposing this improvement as a draft for now.

While we want to support best and recommended practices https://github.com/compose-spec/compose-spec/blob/main/04-version-and-name.md#version-top-level-element-obsolete, we also want to have more coverage for the end users of score-compose. In this case I understand that is for Podman Compose users, which is good feedback. We want to make sure we understand this kind of blockers there and see if we can accommodate.

With that being said, we don't want to add too much burden on the maintenance of this.

So I think your recommendation of testing locally this on your end and keeping this PR as a draft for now while capturing more insights is the right approach.

Also, understanding which versions are involved and not working by default would help too.

Thanks again for your willingness to contribute to Score, @Gordonby!