dav1d: update to 1.5.1

[dogknowsnx]

I successfully tested:

• mpv decoding with libdav1d (at least according to the on-screen info script)
• Opening .avif files with mpv
• Opening .avif or .svg files with swayimg
• Rendering .avif or .svg files with chafa inside foot terminal

Local build testing

• I built this PR locally for my native architecture, (x86_64-glibc)

[dogknowsnx]

Fwiw, I'm not using ffmpeg atm (and the transition to version 7 hasn't been made yet), so I'm not sure what else this PR might entail - just intending to get the update going.

For convenience: https://code.videolan.org/videolan/dav1d/raw/master/NEWS

[Duncaen]

Doesn't look like this needs revbumps?

[dogknowsnx]

Ok, restored common/shlibs as well. The minimum version providing libdav1d.so.7 remains libdav1d-1.3.0_1