Only include metadata on new comfy versions

For #407 since old comfy versions don't support passing metadata (added in #399 )

nodes.py

@@ -1,6 +1,7 @@
 # (c) City96 || Apache-2.0 (apache.org/licenses/LICENSE-2.0)
 import torch
 import logging
+import inspect
 import collections
 
 import nodes
@@ -166,8 +167,14 @@ class UnetLoaderGGUF:
         # init model
         unet_path = folder_paths.get_full_path("unet", unet_name)
         sd, extra = gguf_sd_loader(unet_path)
+
+        kwargs = {}
+        valid_params = inspect.signature(comfy.sd.load_diffusion_model_state_dict).parameters
+        if "metadata" in valid_params:
+            kwargs["metadata"] = extra.get("metadata", {})
+
         model = comfy.sd.load_diffusion_model_state_dict(
-            sd, model_options={"custom_operations": ops}, metadata=extra.get("metadata", {})
+            sd, model_options={"custom_operations": ops}, **kwargs,
         )
         if model is None:
             logging.error("ERROR UNSUPPORTED UNET {}".format(unet_path))