I updated our dependencies like binrw to 0.15, which is pretty nice as
that means we no longer depend on Syn 1.x. I also finally upgraded to
bitflags 2.x, which doesn't really mean anything except we're on
better supported version.
Additionally, I removed some bitrotten code that no longer compiles.
This was mostly benchmark stuff, but since I don't actively keep track
of that I felt it was better to remove it. I can always add it back once
I'm ready to tackle that again.
