Use julia actions in CI?

[mmesiti]

I recently discovered that there is a set of pre-baked github actions curated by the julia community https://github.com/julia-actions. I am not sure this is any better than the current setup, but it could remove the need to use a container and possibly be more robust. To investigate further, maybe.

[mmesiti]

At the moment (https://github.com/mmesiti/PMFRG.jl/blob/MPI/.github/workflows/test.yml) :

• using julia-actions/setup-julia instead of container. This allows to use git lfs without having to install it into the container
• not using julia-runtest. SpinFRGLattices needs to be installed before anyway (not yet found a way to do it, the solution might be more complicated than just running a pair of Julia command as it is done now)
• not using (yet) julia-format. Seems overkill to me (but it could be cool to have an automatic pull request with the formatting instead of a dumb test that check if the code is already formatted)