Reopen PR: Enable Github Actions build of Docker image
I see #252 which would provide prebuilt Docker images. I'm trying to install it on my Raspberry Pi 4 8GB and it has crashed during compilation twice now (taking an hour each time). 

I'd also like to use it in GitHub Actions for tests for [BrianHenryIE/bh-php-monero-explorer](https://github.com/BrianHenryIE/bh-php-monero-explorer) so a prebuilt image would be hugely helpful there too.

I think to merge #252 you need to create/setup accounts on [Docker Hub](https://hub.docker.com/account/signup/) and [GitHub Container registry](https://docs.github.com/en/packages/working-with-a-github-packages-registry/working-with-the-container-registry?ref=josef.codes), then set the secrets in this repo for DOCKER_USERNAME and DOCKER_PASSWORD [in the settings](https://github.com/moneroexamples/onion-monero-blockchain-explorer/settings/secrets/actions) or with [`gh secret set`](https://cli.github.com/manual/gh_secret_set) CLI. 

I'm not certain the current PR will build an ARM image, I'll have to take a closer look at the Workflows. But it would still be helpful as-is.