Replaced outdated macros _PyUnicode_AsString and _PyUnicode_AsStringAndSize
with PyUnicode_AsUTF8 and PyUnicode_AsUTF8AndSize.
diff --git a/Parser/tokenizer.c b/Parser/tokenizer.c
index 8317293..0fa3aeb 100644
--- a/Parser/tokenizer.c
+++ b/Parser/tokenizer.c
@@ -446,7 +446,7 @@
     }
     if (PyUnicode_CheckExact(bufobj))
     {
-        buf = _PyUnicode_AsStringAndSize(bufobj, &buflen);
+        buf = PyUnicode_AsUTF8AndSize(bufobj, &buflen);
         if (buf == NULL) {
             goto error;
         }