Make image build quicker

[sverhoeven]

Is your feature request related to a problem? Please describe.
It takes >50 minutes to build and push the images for x86 and arm64. Just x86 takes 8min. It would be nice if this was quicker.

Describe the solution you'd like
Use native arm64 workflow runner.

Describe alternatives you've considered
Letting Apple M* users build on their own laptops, but hard to troubleshoot.

Additional context

This issue is blocked until arm64 runners are made available for free to open source/public repos.

At end of year it should be available for free for open source projects.
See https://github.blog/2024-06-03-arm64-on-github-actions-powering-faster-more-efficient-build-systems/
and https://docs.docker.com/build/ci/github-actions/multi-platform/#distribute-build-across-multiple-runners

[sverhoeven]

With all the caching it takes 20 minutes, which is fast enough.

[sverhoeven]

With openmm compilation #156 the build takes >30 minutes again

[sverhoeven]

openmm on pypi is available as binary wheel for x86 linux, but not for arm64 linux. Both archs are available on anaconda, which would need a rewrite of the Dockerfile.

[sverhoeven]

Also we could use https://github.com/haddocking/haddock3/pkgs/container/haddock3 aka https://github.com/haddocking/haddock3/blob/main/Dockerfile to copy haddock3 and its deps.
It uses different FROM (webapp usespython:3.9-slim-bookworm and haddock3 uses python:3.12) so we should be careful to copy enough, but not too much.