The runner VMs (Ubuntu et al.) contain plenty of preinstalled software enough to cover most of the needs. There is, e.g. Chrome browser for enabling automated end-to-end testing, if you're into that, and why shouldn't you be.
In overall, if you're satisfied with, say, Travis, Semaphore, or Gitlab CI solutions, there is little need to jump the ship as it won't offer you any remarkable benefits as of now. It's terrific to see Github providing their in-house CI solutions, though, keeping the competition going strong.