QF_only_push_master

Pipeline is firing even when we don't modify the setup.cfg file.

This is because of (from Gitlab CI/CD doc):

You should use rules: changes only with branch pipelines or merge request pipelines. You can use rules: changes with other pipeline types, but rules: changes always evaluates to true when there is no Git push event. Tag pipelines, scheduled pipelines, manual pipelines, and so on do not have a Git push event associated with them. A rules: changes job is always added to those pipelines if there is no if that limits the job to branch or merge request pipelines.

I added an if that checks if we're on master.