Add `SCHED_DEADLINE` and `SCHED_NORMAL` constants to `os` module

Feature or enhancement

Proposal:

This issue suggests adding new os constants.

os.SCHED_DEADLINE

# deadline scheduling
# Set the current schedule to real-time schedule, To be precise, it
# is not real-time scheduling, but it is relatively real-time.
prio = os.sched_param(sched_priority=10)
os.sched_setscheduler(0, os.SCHED_DEADLINE, prio)

SCHED_NORMAL is the same as SCHED_OTHER.
But to run in the old linux, we can't remove SCHED_OTHER, even if it no longer exists in the current main branch.
But we still need to add SCHED_NORMAL, because SCHED_OTHER only exists in the old distribution.

Has this already been discussed elsewhere?

No response given

Links to previous discussion of this feature:

No response

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