Fix "has no member named query_formats" error
Hi! First of all thanks - this filter is great fun!
We have been trying to compile this with a friend and got the following error.
libavfilter/vf_shadertoy.c:571:6: error: ‘AVFilter’ {aka ‘struct AVFilter’} has no member named ‘query_formats’
571 | .query_formats = query_formats,
We fixed it with this. The code was borrowed from other ffmpeg filter source files.