Update output_formatters.py to use gpt-4o's tokenizer

Author: AmgadHasan

src/gitingest/output_formatters.py

@@ -171,7 +171,7 @@ def _format_token_count(text: str) -> Optional[str]:
         The formatted number of tokens as a string (e.g., '1.2k', '1.2M'), or `None` if an error occurs.
     """
     try:
-        encoding = tiktoken.get_encoding("cl100k_base")
+        encoding = tiktoken.get_encoding("o200k_base") # gpt-4o, gpt-4o-mini
         total_tokens = len(encoding.encode(text, disallowed_special=()))
     except (ValueError, UnicodeEncodeError) as exc:
         print(exc)