Dockerize

[asg0451]

Hi! I don't know if you're accepting PRs for this repo, but I'm a daily user of WTFT but i just wish there would be more than 5 trains per station, sometimes, or something. So I'm planning on running my own fork of both MTAPI and WTFT on my home kube cluster, which necessitates dockerizing them. In the interest of open source, I'm willing to contribute these changes upstream -- if you're interested. No worries if not! :)

This PR adds:

• (hopefully) Production-ready Dockerfile with gunicorn
• Github Actions workflow that builds and pushes images to GHCR on each master push (simplest workflow)
• K8s Kustomize-able manifest for either direct use or just as an example

If you have any interest in merging this I can replace asg0451 with jonthornton in a few places.

Thanks for the awesome app btw!