graphicsmagick: update to 1.3.46

graphicsmagick: update to 1.3.46

Security fixes:
- Fix MSL/SVG parsers to use libxml2 SAX handlers, removing archaic
  cruft with potential security issues
- Fix JP2 Jasper max_samples calculation to avoid DoS via huge images
- Apply image dimension resource limits and fix heap write overflow in JXL
- Fix WPG palette buffer allocation (SF bug #750)
- Fix ColorFloodfillImage() to error when clip-mask is present

Bug fixes:
- Fix JPEG CMYK inversion regression introduced in 1.3.43
- Re-implement PNG8 writer with correct indexed-color and binary transparency
- Re-write HEIF reader (AVIF, HEIC) based on heif_image_get_plane_readonly2(),
  adding deep image support and YCbCr/monochrome output
- Fix Hull transform arithmetic overflow regression from Oct 2023
- Fix -crop percentage tiling regression
- Re-enable EXPERIMENTAL_EXIF_TAGS by default with known issues fixed
- Fix Magick++ thread safety regression since 2003 (pthreads support)

New features:
- Add support for newer Artifex urw-base35-fonts (OpenType and Type 1)
- Add ImagesResource limit to control simultaneous loaded images
- Add EXIF Version 3.0 decoding and validation
- Add preliminary MP4 coder with HEIF sequence support
- Require C99 compiler compatibility in build infrastructure

Signed-off-by: Alexandru Ardelean <redacted>