🚨🚨🚨 Limit backtracking in Nougat regexp (#35264)

* Limit backtracking in regexp

* Update

* [run-slow] nougat

* Update

src/transformers/models/nougat/tokenization_nougat_fast.py

@@ -514,7 +514,7 @@ def post_process_single(self, generation: str, fix_markdown: bool = True) -> str
         generation = generation.replace("\n* [leftmargin=*]\n", "\n")
         # Remove lines with markdown headings starting with #, with numerals,
         # and possibly roman numerals with trailing spaces and newlines
-        generation = re.sub(r"^#+ (?:\.?(?:\d|[ixv])+)*\s*(?:$|\n\s*)", "", generation, flags=re.M)
+        generation = re.sub(r"^#+ (?:[\d+\.]+|[ixv\.]+)?\s*(?:$|\n\s*)", "", generation, flags=re.M)
         # most likely hallucinated titles
         lines = generation.split("\n")
         if lines[-1].startswith("#") and lines[-1].lstrip("#").startswith(" ") and len(lines) > 1: