Fixed build error

This line prevents publishing to crates.io

build.rs

@@ -23,13 +23,15 @@ fn main() {
         return;
     }
 
+    /*
     // From libpng/png.h:
     // "If pnglibconf.h is missing, you can copy scripts/pnglibconf.h.prebuilt to pnglibconf.h"
     std::fs::copy(
         "libpng/scripts/pnglibconf.h.prebuilt",
         "libpng/pnglibconf.h",
     )
     .unwrap();
+    */
 
     let mut build = cc::Build::new();