Fix bug in subsetting script

Signed-off-by: Danila Fedorin <danila.fedorin@gmail.com>

chatgpt-subset-one-go.py

@@ -16,8 +16,7 @@ def get_used_characters(files):
     """Collect unique characters from all .html files in the given directory."""
     char_set = set()
     for file in files:
-        full_path = os.path.join(root, file)
-        text = extract_text_from_html(full_path)
+        text = extract_text_from_html(file)
         char_set.update(text)
     return "".join(sorted(char_set))