convert-hf : sort model part names

`os.listdir` is said to list files in arbitrary order.
Sorting the file names should let "model-00009-of-00042.safetensors"
be loaded before "model-00010-of-00042.safetensors".

convert-hf-to-gguf.py

@@ -243,6 +243,8 @@ class Model(Protocol):
             if filename.endswith(suffix):
                 part_names.append(filename)
 
+        part_names.sort()
+
         return part_names
 
     @staticmethod