v1.6.0

Changed

• Improved elixir version support with downgrading to elixir 1.13 by @Argonus in #65
• updated ex_docker_engine_api to latest version that supports elixir 1.13 by @jarlah
• updated Ryuk to latest version 0.6.0 by @jarlah

Full Changelog: v1.5.1...v1.6.0