sysconfig.get_config_var should return Any (#8572)

This can return str, int, None... and maybe more. In the interest of being defensive, have it return Any.

stdlib/sysconfig.pyi

@@ -16,7 +16,7 @@ __all__ = [
     "parse_config_h",
 ]
 
-def get_config_var(name: str) -> str | None: ...
+def get_config_var(name: str) -> Any: ...
 @overload
 def get_config_vars() -> dict[str, Any]: ...
 @overload