Bug#1023646: ffmpeg: add jpeg-xl support

[Mathieu Malaterre <malat@debian.org>]

Source: ffmpeg
Version: 7:5.1.2-1

Please add jpeg-xl support:

* https://github.com/libjxl/libjxl/blob/main/doc/software_support.md#image-libraries

For reference.

* https://github.com/FFmpeg/FFmpeg/search?q=jpeg-xl&type=commits

Thank you !