build: Fix gtk-doc check
build: Fix gtk-doc check

https://gitlab.gnome.org/GNOME/librsvg/-/issues/866

Part-of: <https://gitlab.gnome.org/GNOME/librsvg/-/merge_requests/701>

GNOME/librsvg,GNOME/librsvg,GNOME/librsvg,GNOME/librsvg