Remove version tag in compose file as marked as obsolete by lastest docker compose version

[sabruss]

With the latest version of Docker Compose,

When specifying a version tag in any compose*.yaml, When running any docker compose command a warning appears stating that the version tag is obsolete.

Referring to the Compose documentation here, it appears that this tag has been purely informational for a long time. Some research suggests that it has been obsolete since the release of Docker Compose v1.27.x on 2020-09-10.

Do you think it can be removed safely ?

[dunglas]

Yes. It has already been removed from Symfony Docker and API Platform. You can remove it safely, it's supported by Flex.

[fabpot]

@dunglas Does it mean we should remove this line? https://github.com/symfony/flex/blob/2.x/src/Configurator/DockerComposeConfigurator.php#L239

[dunglas]

Indeed, good catch.