Fixes #12732: destination must be a list (#12746)

even for a single file, the destination must be a list not a string

geonode/assets/management/commands/migrate_file_to_assets.py

@@ -124,7 +124,7 @@ def handle(self, **options):
             logger.info("Updating location field with new folder value")
 
             if len(asset.location) == 1:
-                asset.location = dest
+                asset.location = [dest]
             else:
                 asset.location = [x.replace(source, dest) for x in asset.location]
             asset.save()