Add self argument that is mandatory to [clip_skip] filename pattern.

modules/images.py

@@ -352,7 +352,7 @@ class FilenameGenerator:
         'prompt_no_styles': lambda self: self.prompt_no_style(),
         'prompt_spaces': lambda self: sanitize_filename_part(self.prompt, replace_spaces=False),
         'prompt_words': lambda self: self.prompt_words(),
-        'clip_skip': lambda: opts.data["CLIP_stop_at_last_layers"],
+        'clip_skip': lambda self: opts.data["CLIP_stop_at_last_layers"],
     }
     default_time_format = '%Y%m%d%H%M%S'