bpo-26564: fix obsolete comment in traceback.c (GH-23819)

(cherry picked from commit 40125ab325)

Co-authored-by: Irit Katriel <iritkatriel@yahoo.com>

Python/traceback.c

@@ -623,7 +623,8 @@ PyTraceBack_Print(PyObject *v, PyObject *f)
     return err;
 }
 
-/* Reverse a string. For example, "abcd" becomes "dcba".
+/* Format an integer in range [0; 0xffffffff] to decimal and write it
+   into the file fd.
 
    This function is signal safe. */