Replace chainner_models with Spandrel package (#2146)

* Replace chainner_models with Spandrel

* Update to latest spandrel

* Use spandrel_foss instead

* update spandrel to new FOSS-compliant version

comfy_extras/nodes_upscale_model.py

 import os
-from comfy_extras.chainner_models import model_loading
+from spandrel import ModelLoader, ImageModelDescriptor
 from comfy import model_management
 import torch
 import comfy.utils
@@ -20,7 +20,11 @@ class UpscaleModelLoader:
         sd = comfy.utils.load_torch_file(model_path, safe_load=True)
         if "module.layers.0.residual_group.blocks.0.norm1.weight" in sd:
             sd = comfy.utils.state_dict_prefix_replace(sd, {"module.":""})
-        out = model_loading.load_state_dict(sd).eval()
+        out = ModelLoader().load_from_state_dict(sd).eval()
+
+        if not isinstance(out, ImageModelDescriptor):
+            raise Exception("Upscale model must be a single-image model.")
+
         return (out, )
 
 
@@ -61,7 +65,7 @@ class ImageUpscaleWithModel:
                 if tile < 128:
                     raise e
 
-        upscale_model.cpu()
+        upscale_model.to("cpu")
         s = torch.clamp(s.movedim(-3,-1), min=0, max=1.0)
         return (s,)