Declare compatible with Python 3.8

Fix workflow trying to upload artifact when none was built

Minor changes to task repetition in Task and TaskQueue

Tasks have an `__eq__` method that compares an `_id` attribute, this is
preserved across `copy` which is done when a repeated task is re-added
to the queue.

This can be used to check if a task is in the queue with e.g. `if task
in tasks`, which will evaluate to `True` if a copy of the task is in
the queue, as it would be for a repeated task.

Also, manually re-adding a task to the queue resets its `_called`
attribute so it doesn't raise an exception when next called.

These changes are to support holding a reference to a task that has
`repeat=True`, and being able to check if (a copy of) that task is in
the queue, and being able to cancel and re-add it.

Use a custom ZAP authentication thread

To resolve issues around interpreter shutdown and asyncio

Add repetition functionality to Task and TaskQueue

Release for Python 3.11

workflow: pin macos version to 10.15 for now

This is because xcode 11 is not available on newer macos, and xcode 11
is required for building conda packages. Here in zprocess we don't
actually need to do compilation since we're a pure package, but we'll
keep this in line with the standard workflow across all our projects.

use `_get_fileno()` in more places

to avoid .fileno() failure in jupyter/IDLE

Workaround for raising exceptions with custom arguments

We can't anticipate what their arguments will be, so just return a
RuntimeError in this case.

Almost all exceptions take a single message argument, but custom ones
can do anything they like. The example I came across is pyserial's
serial.serialutil.PortNotOpenError, which accepts no arguments.

Modernise workflow

sync from
rpanderson/workflow-sandbox@f03ea46