Travis CI (https://travis-ci.com/) is a popular continuous integration service that's freely available for public GitHub projects. Integration with GitHub is very simple and it allows you to configure the platform it runs on, such as macOS, Linux, or even iOS.
Travis CI integrates tightly with GitHub, so you only need to log in to GitHub to be able to access it. We'll see how to connect our project to it.
Travis works a bit differently from other CI tools in that it creates independent jobs by starting a new VM. This means that any artifact created for a previous stage needs to be copied somewhere else to be downloaded at the start of the next stage.
This makes things a bit unpractical sometimes, and an easy solution is to build multiple times for each individual job.