Build Arm64 dependencies image

[gassmoeller]

@tjhei @luca-heltai FYI

This PR does:

• update the README.md to recent deal.II versions
• Proposes to add a github actions workflow that:
  • is only manually executed by clicking a button here https://github.com/dealii/docker-files/actions/new
  • builds the dependencies docker image on github actions machines
  • builds both a amd64 and arm64 docker image
  • pushes those docker images both to the github container registry and the docker hub

This change would allow us as a next step to:

• build a deal.II image for both amd64 and arm64
• simplifies rebuilding the images for new deal.II releases

You can see how the final images would look like here: https://github.com/gassmoeller/docker-files/pkgs/container/docker-files (I tested the workflow in my account).

The docker hub upload will not work unless we set up secrets to log into docker hub. If we agree that is a good thing I can do that or someone else can as well. The github container registry upload should word out of the box.

Comments and suggestions are welcome. As discussed with @tjhei I think having a deal.II arm64 image would be worthwhile (because it runs well on the Macs ARM architecture).

[luca-heltai]

Very nice!