Isal

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+ Fix a bug where a filehandle remained opened when ``igzip_threaded.open``
was used for writing with a wrong compression level.
+ Fix a memory leak that occurred when an error was thrown for a gzip header
with the wrong magic numbers.
+ Fix a memory leak that occurred when isal_zlib.decompressobj was given a
wrong wbits value.

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+ Fix a memory leak in the GzipReader.readall implementation.

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+ Make a special case for threads==1 in ``igzip_threaded.open`` for writing
files. This now combines the writing and compression thread for less
overhead.
+ Maximize time spent outside the GIL for ``igzip_threaded.open`` writing.
This has decreased wallclock time significantly.

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+ Fix several errors related to unclosed files and buffers.

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+ Drop support for python 3.7 and PyPy 3.8 as these are no longer supported.
Add testing and support for python 3.12 and PyPy 3.10.
+ Added an experimental ``isal.igzip_threaded`` module which has an
``open`` function.
This can be used to read and write large files in a streaming fashion
while escaping the GIL.
+ The internal ``igzip._IGzipReader`` has been rewritten in C. As a result the
overhead of decompressing files has significantly been reduced and
``python -m isal.igzip`` is now very close to the C ``igzip`` application.
+ The ``igzip._IGZipReader`` in C is now used in ``igzip.decompress``. The
``_GzipReader`` also can read from objects that support the buffer protocol.
This has reduced overhead significantly.

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+ Gzip headers are now actively checked for a BGZF extra field. If found the
block size is taken into account when decompressing. This has further
improved bgzf decompression speed by 5% on some files compared to the
more generic solution of 1.2.0.
+ Integrated CPython 3.11 code for reading gzip headers. This leads to more
commonality between the python-isal code and the upstream gzip.py code.
This has enabled the change above. It comes at the cost of a slight increase
in overhead at the ``gzip.decompress`` function.