Fix ci

[wins1ey]

• Bump actions/checkout and actions/upload-artifact to v4
• Replace devkitpro/devkitppc with extremscorner/libogc2 meaning that libogc2 and libfat don't need to be compiled because they are included in the container
• Install pyelftools using system package manager so a python virtual environment isn't needed

A successful run: https://github.com/wins1ey/contrib-cubiboot/actions/runs/19214530051