gh-133644: Remove `PySys_SetArgv*` for 3.15 by xuantengh · Pull Request #136277 · python/cpython

Which will preserve them in python3dll.c, which is the actual breaking change (or at least the one that can be easily seen in a source diff).

Arguably they should stay in the header files as well, possibly only when Py_LIMITED_API is set. The functionality can change if it needs to, though ideally wouldn't break every existing user.