Warnings interfere with "dmenu" style usage

[ideasman42]

When looking to replace wofi/dmenu with yofi I ran into a problem.

yofi dialog is always printing a warning which interferes with the stdout - used to receive the output of the command.

{options} | yofi dialog

Should output selected_menu_item, instead it outputs a warning, then the menu item.

e.g.

2024-06-23T00:36:18.346367550Z[yofi::window::compositor][WARN] unexpected transform_changed
selected_menu_item

Ideally any warnings should output to the stderr, so the stdout can be relied on for intended output.

Tested with 2.2 stable and my own build of: 0d7af46.