Setup CI/CD for ActivityWatch Server Docker building

Hey, activitywatch server doesnt seem to have a consistently updated docker image on dockerhub. The most recent image on dockerhub (not sure if official) was last updated 2 years ago. I believe that by using CI/CD and automating the docker build process so that a docker image is built for a new release, this would allow the dockerhub images to be kept up to date with any new releases/commits.