libpng-sys-1.1.7 has been yanked.
Unreliable bindings for libpng 1.6.
They're likely to bring sorrow and regret. Please use a native Rust PNG library instead (e.g. LodePNG 2.x).
Bundles libpng 1.6.37 as a fallback. Please check whether this version is still secure before using this package.