Notes on public versus private gitlab runners.  GitLab has a common set of public CI/CD build runners that are shared throughout the entire world.  While this doesn't cost anything, it can be limiting in what they are capable of doing.

For the majority of the time this is ok for open source or experimentation projects, but if the code you are placing on github is used say in the case of a SaaS the only real option for reliability and configuration is to to create a private specific runner set for your organization profile only.