Add a cache to rst.inline_markup_gen()

Author: AlexWaygood

sphinxlint/rst.py

@@ -4,6 +4,7 @@
 - All constants are ALL_CAPS
 - All compiled regexes are suffixed by _RE
 """
+from functools import cache
 
 import regex as re
 
@@ -151,6 +152,7 @@
 UNICODE_ALLOWED_AFTER_INLINE_MARKUP = r"\p{Pe}\p{Pi}\p{Pf}\p{Pd}\p{Po}"
 
 
+@cache
 def inline_markup_gen(start_string, end_string, extra_allowed_before=""):
     """Generate a regex matching an inline markup.