Docker image arm compability

[EliasB-NU]

Hi, I host all of my projects on arm64 cloud servers, currently I have to clone the repository on my server and compile it myself. It would be super useful, if you add support for arm. I don't completely understand your github workflow, so I cannot add it myself, if you need some inspiration on how I do it, here is a my github actions file for compiling for arm64 and amd64: https://github.com/EliasB-NU/rcj-gamesite/blob/dev/.github/workflows/deploy.yaml.

[fliiiix]

If someone wants to create a pull request for that go ahead.

[EliasB-NU]

#918