- update to 2.1.3:
* Fixed a regression introduced by 2.0 beta1[7] whereby cjpeg compressed PGM
input files into full-color JPEG images unless the `-grayscale` option was
used.

* cjpeg now automatically compresses GIF and 8-bit BMP input files into
grayscale JPEG images if the input files contain only shades of gray.

* The build system now enables the intrinsics implementation of the AArch64
(Arm 64-bit) Neon SIMD extensions by default when using GCC 12 or later.

* Fixed a segfault that occurred while decompressing a 4:2:0 JPEG image using
the merged (non-fancy) upsampling algorithms (that is, with
`cinfo.do_fancy_upsampling` set to `FALSE`) along with `jpeg_crop_scanline()`.
Specifically, the segfault occurred if the number of bytes remaining in the
output buffer was less than the number of bytes required to represent one
uncropped scanline of the output image. For that reason, the issue could only
be reproduced using the libjpeg API, not using djpeg.