Updated libpng to 1.6.40

Author: radarhere

config.sh

@@ -6,7 +6,7 @@ ARCHIVE_SDIR=pillow-depends-main
 # Package versions for fresh source builds
 FREETYPE_VERSION=2.13.0
 HARFBUZZ_VERSION=7.3.0
-LIBPNG_VERSION=1.6.39
+LIBPNG_VERSION=1.6.40
 JPEGTURBO_VERSION=2.1.5.1
 OPENJPEG_VERSION=2.5.0
 XZ_VERSION=5.4.3