Advanced options don't work

[k128]

Windows 10
Python 3.11.2
pillow_avif_plugin-1.3.1-cp311-cp311-win_amd64.whl

Trying to pass any of the SVT-specific parameters has no effect. I've tried several parameters and ways of passing them. For example, these all produce the same output:
im.save('test.avif',save_all=True,codec='svt')
im.save('test.avif',save_all=True,codec='svt',advanced={'n':2})
im.save('test.avif',save_all=True,codec='svt',advanced={'-n':2})
im.save('test.avif',save_all=True,codec='svt',advanced={'n':'2'})
im.save('test.avif',save_all=True,codec='svt',advanced={'-n':'2'})
im.save('test.avif',save_all=True,codec='svt',n=2)
im.save('test.avif',save_all=True,codec='svt',n=2)

[fdintino]

I think that libavif doesn't yet support passing advanced options into the svt codec.