Build using Github actions

[Emersont1]

We're currently using travis to build, it'll be easier to just use github actions. I will add this in a pull request soon

We currently have a second repository for the built content ( URN/urn-history-project-gh-pages ) This should really just be part of the gh-pages branch of the main repo.

[johnathan99j]

Defo need to move away from Travis.

I feel like I had a reason for a separate private repo for the built version 🤔 if only I could remember why 😅