The file <examples/faketrello/docs/screenshot.png> contains an ICC profile, copyrigh Apple Inc. with no licensing - i.e. that embedded code is copyright-protected and is not licensed for free redistribution or reuse.
Please strip the ICC profile from that image.
If curious (as others have been when I filed similar reports), the way I detect such issues is with the command-line tool exiftool part of the Perl library Image::ExifTool, available e.g. in Debian-based distributions as package libimage-exiftool-perl.