[3.12] gh-103417: Fix the scheduler example (GH-111497) (GH-115908)

Arguments to enterabs() are specified as Unix time.
If the scheduler use the time.monotonic timer, the code will take
decades to complete.
(cherry picked from commit cb287d3421)

Co-authored-by: mauricelambert <50479118+mauricelambert@users.noreply.github.com>

Doc/library/sched.rst

@@ -36,7 +36,7 @@ scheduler:
 Example::
 
    >>> import sched, time
-   >>> s = sched.scheduler(time.monotonic, time.sleep)
+   >>> s = sched.scheduler(time.time, time.sleep)
    >>> def print_time(a='default'):
    ...     print("From print_time", time.time(), a)
    ...