fix(nova): use distro supplied libvirt-python (#742)

diff --git a/flake.nix b/flake.nix
index 8964172..a11b761 100644
--- a/flake.nix
+++ b/flake.nix
@@ -15,6 +15,7 @@
         {
           devShell = pkgs.mkShell {
             buildInputs = with pkgs; [
+              earthly
               vendir
             ];
           };