Ubuntu CI has newer packages

[jordancarlin]

The installation CI is using the default GitHub Actions runners for Ubuntu installation tests. While working on #1258, I discovered that these images come with newer versions of some packages that have been manually installed and are not normally available in the default Ubuntu package repos.

We should update the Ubuntu installation CI runs to directly use a clean Ubuntu docker image to avoid this. It led me to believe that the new version of sail worked, but that was actually only because GitHub preinstalls CMake 3.31 (3.16 is what is actually available from apt).

[jordancarlin]

Another reason we should switch to docker images for all CI tests is apparently Ubuntu 20.04 GitHub Actions CI is beginning deprecation process February 1: actions/runner-images#11101

Eventually we'll need to think about our own deprecation policy for what distros we test against/support. Official EOL for Ubuntu 20.04 is May 31.

[PietDelaney]

I had a problem like this and change to $PATH to put the wally version in the beginning of the search path

[jordancarlin]

That's a good suggestion, but since we already use Docker images to test on all non-Ubuntu distros, it seems easier to keep it consistent and just switch Ubuntu over to standard Docker images as well. Especially because GitHub Actions is deprecating the Ubuntu 20.04 runner before the actual EOL of Ubuntu 20.04, so we need a new way to test it.