twist_mux: 0.0.4-0 in 'hydro/distribution.yaml' [bloom]

Increasing version of package(s) in repository `twist_mux` to `0.0.4-0`:

- upstream repository: https://github.com/ros-teleop/twist_mux.git
- release repository: https://github.com/ros-gbp/twist_mux-release.git
- distro file: `hydro/distribution.yaml`
- bloom version: `0.5.12`
- previous version for package: `0.0.2-0`

## twist_mux

```
* Add missed test dependencies on rospy, rostopic
* Contributors: Enrique Fernandez
```