[3.15] gh-126547: pre-allocate version number for unicode type (GH-157781) (GH-157812)

(cherry picked from commit c2e740a)

Co-authored-by: Inada Naoki <songofacandy@gmail.com>

Author: miss-islington

Objects/unicodeobject.c

@@ -14071,6 +14071,7 @@ PyTypeObject PyUnicode_Type = {
     0,                            /* tp_alloc */
     unicode_new,                  /* tp_new */
     PyObject_Free,                /* tp_free */
+    .tp_version_tag = _Py_TYPE_VERSION_STR,
     .tp_vectorcall = unicode_vectorcall,
     ._tp_iteritem = unicode_iteritem,
 };