gfileutils: Add missing ‘Since’ line to g_canonicalize_filename() docs
gfileutils: Add missing ‘Since’ line to g_canonicalize_filename() docs

I missed this in code review.

Signed-off-by: Philip Withnall <29c2a2ac2a854b9cf047275aa9de346d096be2e0@endlessm.com>
Reviewed-by: nobody

endlessm/glib,endlessm/glib,endlessm/glib,endlessm/glib,endlessm/glib