nixos/virtualisation: use systemd-networkd for OCI

Changed files
+4
nixos
modules
virtualisation
+4
nixos/modules/virtualisation/oci-common.nix
···
networking.timeServers = [ "169.254.169.254" ];
services.openssh.enable = true;
+
+
# Otherwise the instance may not have a working network-online.target,
+
# making the fetch-ssh-keys.service fail
+
networking.useNetworkd = true;
}