2.5.2

This is a release candidate for 2.6.0.

In addition to new CMake support by @madebr and many bug fixes, here are the highlights since the last release:

• Added stb_image as the default backend for JPG and PNG images loading.
  To use libpng and libjpg instead configure using --disable-stb-image
• Added IMG_LoadSizedSVG_RW()
• Added support for AVIF images (https://github.com/AOMediaCodec/libavif)
• Added IMG_ReadXPMFromArrayToRGB888()
• Added support for JXL images (https://jpegxl.info/)
• Added support for QOI images (https://qoiformat.org/)
• Fixed XCF regression introduced in 2.0.5
• Added support for loading animated GIFs
• LoadBMP() now loads files using SDL2
• Allow using libwebpdecoder instead libwebp.