New comment by ericonr on void-packages repository

https://github.com/void-linux/void-packages/pull/25088#issuecomment-699545102

Comment:
This is missing several dependencies. After installing, I got:

```
Traceback (most recent call last):
  File "/bin/setzer", line 19, in <module>
    gi.require_version('Gtk', '3.0')
AttributeError: module 'gi' has no attribute 'require_version'
```

After installing `python3-gobject`, I now have:

```
Traceback (most recent call last):
  File "/bin/setzer", line 26, in <module>
    from setzer.workspace.workspace import Workspace
  File "/usr/lib/python3.8/site-packages/setzer/workspace/workspace.py", line 22, in <module>
    from setzer.document.document import Document, LaTeXDocument, BibTeXDocument
  File "/usr/lib/python3.8/site-packages/setzer/document/document.py", line 25, in <module>
    import setzer.document.document_viewgtk as document_view
  File "/usr/lib/python3.8/site-packages/setzer/document/document_viewgtk.py", line 20, in <module>
    gi.require_version('GtkSource', '4')
  File "/usr/lib/python3.8/site-packages/gi/__init__.py", line 129, in require_version
    raise ValueError('Namespace %s not available' % namespace)
ValueError: Namespace GtkSource not available
```