Update to zbus 5.x

https://github.com/dbus2/zbus/releases/tag/zbus-5.0.0

Now requires `pub` on uses of `#[proxy]` if the generated types should
be `pub`.

hostname1/src/lib.rs

@@ -26,7 +26,7 @@ use zbus::proxy;
 	default_service = "org.freedesktop.hostname1",
 	default_path = "/org/freedesktop/hostname1"
 )]
-trait Hostname1 {
+pub trait Hostname1 {
 	/// Describe method
 	fn describe(&self) -> zbus::Result<String>;