[BUG] missing dependency on Ubuntu 20.04

[matemat13]

Describe the bug
The sound switcher will crash with the following error:

Traceback (most recent call last):
  File "/usr/local/bin/indicator-sound-switcher", line 32, in <module>
    from indicator_sound_switcher.indicator import SoundSwitcherIndicator, APP_ID
  File "/usr/local/lib/python3.8/dist-packages/indicator_sound_switcher/indicator.py", line 21, in <module>
    from .config import Config, KeyboardManager
  File "/usr/local/lib/python3.8/dist-packages/indicator_sound_switcher/config.py", line 8, in <module>
    gi.require_version('Keybinder', '3.0')
  File "/usr/lib/python3/dist-packages/gi/__init__.py", line 129, in require_version
    raise ValueError('Namespace %s not available' % namespace)
ValueError: Namespace Keybinder not available

after a clean install using sudo python3 setup.py install on Ubuntu 20.04. Running sudo apt install gir1.2-keybinder-3.0 fixes this problem. It seems that this dependency is missing in the install script.

To Reproduce

1. Get a clean installation of Ubuntu 20.04.
2. Clone the indicator-sound-switcher and checkout the latest release (2.3.4).
3. Install indicator-sound-switcher from source using the command sudo python3 setup.py install as per the instructions in the installation part of the documentation.
4. Run indicator-sound-switcher from the terminal.

Expected behavior
The indicator-sound-switcher will successfully run.

Desktop (please complete the following information):

• OS: Ubuntu 20.04.
• Desktop environment: i3wm 4.18
• Sound Switcher Indicator version: 2.3.4

Indicator log:
Cannot fetch it since indicator-sound-switcher crashes after startup with the above error.

[yktoo]

Unfortunately, you don't seem to be able to install OS packages using setup.py, at least not with distutils. I will add the information to the Installation document that one has to install dependencies themselves prior to running setup.py.