Work on a successor for this which uses a Docker image with prebuilt GAP, to reduce overhead

[fingolfin]

No description provided.

[wilfwilson]

These docker images would ideally also have the GAP manuals prebuilt, too.

[fingolfin]

@limakzi was interested in looking into allowing GAP package CI jobs to use docker images. That would be awesome. I don't know if that would mean updating the setup-gap action, or require a change to CI files that switches them to Docker files (and then perhaps can dispense with setup-gap). But either would be nice.

[limakzi]

First sketch of containers is here:

• https://github.com/limakzi/gap-docker/actions/runs/10723164174
• https://github.com/limakzi/gap-docker/blob/main/src/dockerfiles/ubuntu-2204-lts/Dockerfile

I think, supporting Ubuntu 22.04 LTS is sufficient enough.