Compose schema version 3.8 support

[chris-crone]

Add support for Compose schema version 3.8 to bring in line with Docker CLI.

See: docker/cli#1410

[sirlatrom]

Also see docker/cli#1746 (another new field in 3.8)

[sirlatrom]

I'm hoping this one will make it in: docker/cli#1783, so in case it looks like it will, I'll be happy to contribute its counterpart in docker-compose.

[chris-crone]

@sirlatrom that'd be great, thanks!

[sirlatrom]

@sirlatrom that'd be great, thanks!

As soon as I get an LGTM from @thaJeztah on docker/cli#1783, I'll push a PR for Compose 3.8. AFAICT it's just a bit of admin-like work by copying over the spec JSON file and adding references to it in a few places.

[aldoborrero]

Any news on this issue? Is somebody working on it?

[sirlatrom]

I believe #6823 resolves this issue.