disko-config: set dnode size auto

disko/disko-config.nix

@@ -112,6 +112,7 @@ assert lib.assertMsg (enableCeph -> enableLuks) "Ceph requires Luks!";
                 options = {
                   canmount = "on";
                   compression = "zstd";
+                  dnodesize = "auto";
                   normalization = "formD";
                   xattr = "sa";
                   inherit mountpoint;