Bump dbus from 0.8.4 to 0.9.0 (#296)

* Bump dbus from 0.8.4 to 0.9.0

Bumps [dbus](https://github.com/diwic/dbus-rs) from 0.8.4 to 0.9.0.
- [Release notes](https://github.com/diwic/dbus-rs/releases)
- [Commits](https://github.com/diwic/dbus-rs/compare/dbus-v0.8.4...dbus-v0.9.0)

Signed-off-by: dependabot-preview[bot] <support@dependabot.com>

* migrate to dbus/dbus-tree 0.9.0

Co-authored-by: dependabot-preview[bot] <27856297+dependabot-preview[bot]@users.noreply.github.com>
Co-authored-by: Henrik Friedrichsen <henrik@affekt.org>

src/main.rs

@@ -17,8 +17,6 @@ extern crate tokio_timer;
 extern crate unicode_width;
 extern crate webbrowser;
 
-#[cfg(feature = "mpris")]
-extern crate dbus;
 
 #[macro_use]
 extern crate serde;