Add more builds to GitHub Actions

[mkoeppe]

• [x] conda-forge
• [x] homebrew (cask = Sage binary distribution)
• [x] ubuntu/debian
• [x] sagemath/sagemath docker image - see: #28909 - Allow overriding "when building, check that user isn't root" for use in Docker containers with configure --enable-build-as-root
• [x] fedora - Docker Hub - - https://hub.docker.com/_/fedora
• [ ] nixos/nix - Docker Hub - https://hub.docker.com/r/nixos/nix/
• [ ] archlinux - Docker Hub - https://hub.docker.com/_/archlinux/
• [ ] sagemathinc/cocalc - Docker Hub - https://hub.docker.com/r/sagemathinc/cocalc/
• [ ] cschwan/sage-on-gentoo: (Unofficial) Gentoo Overlay for Sage- and Sage-related ebuilds - https://github.com/cschwan/sage-on-gentoo
• [ ] sage binary distributions, on various host distributions

References:

• Distribution - Sage Wiki - https://wiki.sagemath.org/Distribution
• sagemath package versions - Repology - https://repology.org/project/sagemath/versions