Instead of just bumping ubuntu-18.04 to 20.04, I took a different route. These builds are for testing build compatibility, nothing more. Publishing the resulting binaries for users to download is a nice bonus only. So I went ahead and used GHA's Docker feature to run these builds on simulated older ubuntu releases (16.04 for now). This seems to work rather well, just sometimes a tiny bit slower due to having to install additional system packages. The published binaries are now also much more widely compatible with different systems.
The current workflow won't run anymore.
Instead of just bumping ubuntu-18.04 to 20.04, I took a different route. These builds are for testing build compatibility, nothing more. Publishing the resulting binaries for users to download is a nice bonus only. So I went ahead and used GHA's Docker feature to run these builds on simulated older ubuntu releases (16.04 for now). This seems to work rather well, just sometimes a tiny bit slower due to having to install additional system packages. The published binaries are now also much more widely compatible with different systems.
I based this PR on #895 (the first commit here).