setup.py uses ast.Str, which was removed in Python 3.14. As a result, attempting to build or install html5lib under Python 3.14 fails with an AttributeError, similar to below:

>   File"setup.py", line 93,in<module>>     isinstance(a.value, ast.Str)):>                         ^^^^^^^> AttributeError: module'ast' has no attribute'Str'