Replaced outdated macros _PyUnicode_AsString and _PyUnicode_AsStringAndSize
with PyUnicode_AsUTF8 and PyUnicode_AsUTF8AndSize.
diff --git a/Python/future.c b/Python/future.c
index d94b23d..9c1f430 100644
--- a/Python/future.c
+++ b/Python/future.c
@@ -21,7 +21,7 @@
     names = s->v.ImportFrom.names;
     for (i = 0; i < asdl_seq_LEN(names); i++) {
         alias_ty name = (alias_ty)asdl_seq_GET(names, i);
-        const char *feature = _PyUnicode_AsString(name->name);
+        const char *feature = PyUnicode_AsUTF8(name->name);
         if (!feature)
             return 0;
         if (strcmp(feature, FUTURE_NESTED_SCOPES) == 0) {