/usr/include/gobject-introspection-1.0/ is in libgirepository1.0-dev 1.50.0-1+b1.
This file is owned by root:root, with mode 0o755.
..
/usr/include/gobject-introspection-1.0/giarginfo.h
/usr/include/gobject-introspection-1.0/gibaseinfo.h
/usr/include/gobject-introspection-1.0/gicallableinfo.h
/usr/include/gobject-introspection-1.0/giconstantinfo.h
/usr/include/gobject-introspection-1.0/gienuminfo.h
/usr/include/gobject-introspection-1.0/gifieldinfo.h
/usr/include/gobject-introspection-1.0/gifunctioninfo.h
/usr/include/gobject-introspection-1.0/giinterfaceinfo.h
/usr/include/gobject-introspection-1.0/giobjectinfo.h
/usr/include/gobject-introspection-1.0/gipropertyinfo.h
/usr/include/gobject-introspection-1.0/giregisteredtypeinfo.h
/usr/include/gobject-introspection-1.0/girepository.h
/usr/include/gobject-introspection-1.0/girffi.h
/usr/include/gobject-introspection-1.0/gisignalinfo.h
/usr/include/gobject-introspection-1.0/gistructinfo.h
/usr/include/gobject-introspection-1.0/gitypeinfo.h
/usr/include/gobject-introspection-1.0/gitypelib.h
/usr/include/gobject-introspection-1.0/gitypes.h
/usr/include/gobject-introspection-1.0/giunioninfo.h
/usr/include/gobject-introspection-1.0/giversionmacros.h
/usr/include/gobject-introspection-1.0/givfuncinfo.h