graphics/pngcheck: Update to 3.0.3

ChangeLog: http://www.libpng.org/pub/png/src/pngcheck-3.0.3.CHANGELOG

Fixed a divide-by-zero crash bug (and probable vulnerability) in interlaced
images with extra compressed data beyond the nominal end of the image data.

PR: 268031
Reported by: cyberbotx@cyberbotx.com (maintainer)
MFH: 2022Q4 (bugfix release)