Release libpng version 1.6.57
fix: Prevent integer overflow in rowbytes computation
fix: Prevent integer overflow in rowbytes computation
fix: Handle getter-to-setter aliasing in append-style chunk setters
chore: Rerun `./autogen.sh --maintainer`
fix: Handle self-referencing pointers in getter-to-setter aliasing
fix: Handle getter-to-setter aliasing in append-style chunk setters
chore: Rerun `./autogen.sh --maintainer`