Lightweight CI/CD Tool (Targeting Docker on a Raspberry Pi)

Anybody have recommendations for a lightweight CI/CD service that I can run on a Raspberry Pi with 8GB memory?

I'd like to run it in Docker, and I'm the only client --- it doesn't matter to me if builds have to queue/if there's only one worker "node" on the pi, but I just want to be able to do github action-like stuff with my gitea server.