`GstBinExt::add` and `TagSetterExtManual::add` clash

I naively copied code from the transmux.rs example into a project of mine and got "add() wants 2 arguments" - having only these imports:

use gst::{element_error, prelude::*};
use gstreamer as gst;

(rustfmt decided to swap these, not my idea)

Anyway it took me a minute to figure out that here:

https://gitlab.freedesktop.org/gstreamer/gstreamer-rs/-/blob/c4dc549a5ee6ea17a96dd5e8bd2e90b0108eec0f/examples/src/bin/transmux.rs#L102-105

...the right method is GtkBinExt::add. I got it to work for me by using UFCS:

        GstBinExt::add(pipeline, &demuxer).expect("Failed to build remux pipeline");

...but @slomo asked me to open an issue, so here we are!