added podman as the oci-runtime

modules/virtualization/podman.nix

@@ -1,12 +1,16 @@
 { pkgs, ... }:
 
 {
-  virtualisation.podman = {
+  virtualisation = {
+    oci-containers.backend = "podman";
+    containers.registries.search = [ "docker.io" ];
+    podman = {
       enable = true;
 
       dockerCompat = true;
       defaultNetwork.settings.dns_enabled = true;
     };
+  };
 
   # For rootless containers
   security.unprivilegedUsernsClone = true;