Publish a container image

[jasonprado]

Consider publishing containers of the backend and frontend webservers to a container registry so the app can be easily deployed in a container-based environment like Kubernetes.

[j4qfrost]

Those already exist here ghcr.io/openpredictionmarkets/socialpredict-frontend and ghcr.io/openpredictionmarkets/socialpredict-backend

Release notes haven't been posted for them yet because there hasn't been an uptick for versions.