Script to remove kicad 6 incompatible files

[kasbah]

I noticed that when I run ./update there's now a bunch of files that start with (footprint that cause footprint loading to fail completely in KiCad 6.0.10 and earlier. You can reproduce this locally by running python load_all.py where you'll get an IO_ERROR.

My previous strategy was to remove repos when they use unstable features, but we lose a lot of footprints that way that are actually still compatible. It's also more work for me. Would be better to have a script to remove these files.

[kasbah]

https://github.com/mvnmgrx/kiutils might be a good library to use.

[kasbah]

I guess even better would be if we could reset the sub-modules to versions just before they broke compatibility.