This repository builds binary artifacts for the libportaudio project. This repository has a default .travis.yml file that can be used to build binary artifacts on Travis CI. You will however need to setup the release upload manually. See https://docs.travis-ci.com/user/deployment/releases/.
If you don't wish to use travis, you can use the build_tarballs.jl file manually and upload the resulting artifacts to a hosting provider of your choice.