feat: adds docker-compose support for environment maps

[mstruk]

This patch allows using the following syntax in docker-compose:

• Decimal value for version (e.g. version: '3.5')
• List for entrypoint (e.g. entrypoint: [], or entrypoint: [/bin/sh, -c, echo]
• Map for environment

[bartoszmajsak]

This LGTM but would like to hear an opinion from @lordofthejars.

Many thanks @mstruk for your contribution!