GitHub Actions is a continous-integration service by GitHub. You can create actions that other people use in order to e.g. test their code.
Let's say, I license a github action with GNU GPLv3.
Do people using this action need to open-source and license their whole repository with GPL or is this just the case if they e.g. fork my action?
They just include the action by adding something like this to a
- using: myusername/myaction
This does not redistribute my code or create binaries or something like that.