Revert "pythongh-106023: Update What's New in 3.13: _PyObject_FastCall() (python#117633)" (python#117676)

This reverts commit 9a12f5d.

I was wrong: the _PyObject_FastCall() function was removed. But we
kept the _PyObject_FastCallDict() function.

Author: vstinner

Doc/whatsnew/3.13.rst

@@ -2030,6 +2030,11 @@ Removed
 
   (Contributed by Victor Stinner in :gh:`105182`.)
 
+* Remove private ``_PyObject_FastCall()`` function:
+  use ``PyObject_Vectorcall()`` which is available since Python 3.8
+  (:pep:`590`).
+  (Contributed by Victor Stinner in :gh:`106023`.)
+
 * Remove ``cpython/pytime.h`` header file: it only contained private functions.
   (Contributed by Victor Stinner in :gh:`106316`.)