add apt update to preview action template

[mbtaylor]

I don't have a deep understanding of the CI here, but making a change equivalent to this fixed a preview build failure for AuthVO, so I guess the same edit should be in place in the upstream template.

[msdemlei]

On Fri, Jul 11, 2025 at 08:40:24AM -0700, Mark Taylor wrote: I don't have a deep understanding of the CI here, but making a change equivalent to this fixed a preview build failure for AuthVO, so I guess the same edit should be in place in the upstream template.

The apt update is reasonable; one should probably not assume that the package DB that comes with the base image is up-to-date, and if it is not and some of our dependencies have been updated since the base image was built, our CI will fail. I'd approve and merge this except: @gmantelet, should anything else change, too? And perhaps more importantly, are you sure the sudo is required? Most container machinery I know about has basically root only. Thanks for having a look if you can...