Update CI action & runner versions

[ars-ka0s]

In addition to the CodeQL changes needed from #461, also need to make two other changes to the CI configuration:

• Remove Ubuntu 18.04 runner as it was deprecated last year and was recently completely removed per actions/runner-images#6002, which causes timed out/failed builds.
• Bump the actions/checkout and actions/upload-artifact to v3 to use a newer supported NodeJS version.

This resolves several errors/warnings returned when the action runs that aren't related to issues with the build itself.

[ars-ka0s]

Rebased to current dev.

Dropped the one commit removing the 18.04 runner as it was eventually addressed in b1b3e85 but the other two are still needed.