I have a single solution for this site that contains WebApp, WebJob and Database project type, along with the standard class libraries.

The Database does not need to be part of the build. In fact, the build process could not find and restore the correct library, so the action failed.

There is probably a way to install the required libraries, but the project is not needed, so it seemed easier just to remove it from the solution in the github action.

Removing the project is simple using donet sln remove, which I didn't even know existed until I needed it. My build action now checks out the repo twice. Once for the webapp and once for the webjob. No need to clutter up the separate projects with un-needed files.