add pystampas image for experiment

[csakka]

This pull request integrates the PySTAMPAS image for experimental testing on OSG

[rynge]

@csakka It looks like that container is private. Syncing to OSG only works for public images (as they will be pushed to a public CVMFS repo).

[csakka]

I updated the CI to fix the authentication issue with containers.ligo.org by adding the necessary docker login command, ensuring the image is accessible and public.

[rynge]

Still failing for me:

$ docker pull containers.ligo.org/pystamp/pystampas:pystampas_osg_CI
Error response from daemon: Head "https://containers.ligo.org/v2/pystamp/pystampas/manifests/pystampas_osg_CI": denied: access forbidden

[csakka]

I just did a test and pulled the pystampas image in a pipeline. For it to work, I had to add USERNAME and TOKEN to my CI/CD variables and ensure Docker logs in beforehand with this script:

`before_script:

• echo "$TOKEN" | docker login containers.ligo.org -u "$USERNAME" --password-stdin`

So, this image is indeed private, as the project's visibility is set to "internal." This automatically makes any image created from the repository private.
Does the Run ./.github/actions/docker-images-verification stage in the repository not have the access credentials for LIGO?

[rynge]

No, this is a general OSG/PATh tool, so no LIGO credentials. The reason we do not allow private repositories here is that the image will be synchronized to the public CVMFS file system. We don't want open a private image to go to a more open environment.

If you want to keep that image private, one solution is to convert it to sif (apptainer build ...) and then ship that sif with your jobs (authenticated OSDF, transfer_input_files, ...).