ci nix: avoid the failure

added easyfix packaging tests labels

I'm getting into really weird errors when using the new image, with lua(jit)'s os.tmpname failing (also some similar knot-dns steps). I don't feel like putting much work into it now, so let's avoid the errors in CI until that's resolved. Nix version is practically irrelevant here.

merged

mentioned in commit e2aea742

mentioned in commit packaging/apkg@f6cf2f53

mentioned in commit packaging/apkg@3e04907d