Janus

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- Implement ``.shutdown(immediate=False)`` for both sync and async APIs 720

The change is not fully backward compatible:

1. If the queue is closed, ``janus.AsyncQueueShutDown`` and
``janus.SyncQueueShutDown`` exceptions are raised instead of ``RuntimeError``.

2. Both sync and async ``.task_done()`` and ``.join()`` don't raise any exception
on queue shutdown/closing anymore; it is compatible with shutdown behavior
of stdlib sync and async queues.

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- Optimize internal implementation for a little speedup 699

- Make not-full and not-empty notifications faster 703

- Add ``.aclose()`` async method 709

- Reduce notifications for a minor speedup 704

- Allow ``janus.Queue()`` instantiation without running asyncio event loop 710

- Remove sync notifiers for a major speedup 714

- Fix hang in ``AsyncQueue.join()`` 716

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- Drop Python 3.7 and 3.8 support

- janus now works on Python 3.9-3.13

- Reexport SyncQueueEmpty, SyncQueueFull, AsyncQueueEmpty, and AsyncQueueFull names 680

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- Drop Python 3.6 support

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- Add SyncQueue and AsyncQueue Protocols to provide type hints for sync and async queues 374

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- Fix Python 3.10 compatibility 358