Add Github Actions docker builds

[brettjenkins]

Hey,

I've added this github action to automatically build the docker images and add them to the github package repository, so people can just pull from there rather than having to build the docker images locally - useful for me as I want to run this in kubernetes so not easy to build on the fly!

It's a bit basic, it just pushes a new latest tag when a push happens on the main branch, but it's a good starting point. It will push all 4 images to ghcr.io/plambrechtsen/pethublocal-mqtt/msgs/web/pethub)

[plambrechtsen]

Hi @brettjenkins thanks for this, I had planned to add GHA for code sanity and building docker image at some point when I got around to it. Have been working on quite a major change where I have refactored the code for the most part from the ground up and should only need one container or run it in a venv with python 3.8+ if folks wanted to use their existing Mosquitto broker and just drop the required settings. Should make deploying it much easier for me to maintain as I have pytests testing each component as well. It's been a slow journey due to family / work commitments but I haven't pushed anything yet as it still isn't functional and passing all end to end tests. I'll keep this open for a while, and when it all is ready to go should be good to merge.

[brettjenkins]

Hey @plambrechtsen - makes sense, I recently purchased a hub which was on revision 009, so managed to use your project to get the key which I've saved for future use. Using the cloud at the moment, but quite keen to go all local with this project in the future :)

Feel free to edit this PR to just build that one docker image when it's done - hopefully i've just reduced your workload by a little :)

Thanks, Brett