/usr/share/doc/libstrigihtmlgui-dev/changelog.Debian.gz is in libstrigihtmlgui-dev 0.7.7-1.1ubuntu3.
This file is owned by root:root, with mode 0o777.
It is a symlink to /usr/share/doc/libstrigihtmlgui-dev/../libsearchclient0/changelog.Debian.gz