v0.1.5

Notable changes:

• rewrite bashbrew children and bashbrew parents (#55)
• initial basic GitHub Action for getting bashbrew built and installed (#57)

(See https://github.com/docker-library/bashbrew/blob/v0.1.5/scripts/bashbrew-host-arch.sh for a useful script that can help determine the appropriate binary to download for a given environment dynamically.)