Isal

+ Fix an error that occurred in the ``__close__`` function when a threaded
writer was initialized with incorrect parameters.

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+ Fix a bug where flushing files when writing in threaded mode did not work
properly.
+ Prevent threaded opening from blocking python exit when an error is thrown
in the calling thread.

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+ Include a patched ISA-L version 2.31. The applied patches make compilation
and wheelbuilding on MacOS ARM64 possible.
+ Fix a bug where READ and WRITE in isal.igzip were inconsistent with the
values in gzip on Python 3.13
+ Small simplifications to the ``igzip.compress`` function, which should lead
to less overhead.

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+ Fix a bug where streams that were passed to igzip_threaded.open where closed.

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+ Fix a bug where compression levels for IGzipFile where checked in read mode.

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+ Fix a bug where append mode would not work when using
``igzip_threaded.open``.