pixbuf-loader: Avoid extra copy by turning slice into Bytes without to_vec()
pixbuf-loader: Avoid extra copy by turning slice into Bytes without to_vec()

Part-of: <https://gitlab.gnome.org/GNOME/librsvg/-/merge_requests/722>

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