• 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.