Configure version of composer to use (1 vs 2)

[gertvdb]

Some packages are not compatible with composer 1 or 2. I can do a composer self-update --2 inside the container after it starts but this could lead to another developer using a different version of composer.

I would be awesome if we could force a composer version in the docker-compose file

[gertvdb]

I found latest tag has composer 2, so I can switch tags.

https://github.com/wodby/php/issues/121

[devkinetic]

So I have been doing this, but it wouldn't be too hard to set this up to be configured.

As a simple answer, officially documenting what those tags were in the Readme would be helpful for new users of the project.