New issue by jkoderu-git on void-packages repository

https://github.com/void-linux/void-packages/issues/25609

Description:
<!-- Don't request update of package. We have a script for that. https://alpha.de.repo.voidlinux.org/void-updates/void-updates.txt . However, a quality pull request may help. -->
### System

* xuname:  
  ``Void 5.8.14_1 x86_64 AuthenticAMD notuptodate rDFF``
* package:  
  ``quodlibet-4.3.0_2``

### Expected behavior
Player opens

### Actual behavior
```
E: 1.245: util.importhelper.load_dir_modules: feedparser.py:93:<module>: AttributeError: module 'base64' has no attribute 'decodestring'
E: 1.933: errorreport.main.errorhook: feedparser.py:93:<module>: AttributeError: module 'base64'has no attribute 'decodestring'
```
### Steps to reproduce the behavior

Revision `2` with Python3.9 is broken, revision `1` worked good.

> base64.encodestring() and base64.decodestring(), aliases deprecated since Python 3.1, have been removed: use base64.encodebytes() and base64.decodebytes() instead. (Contributed by Victor Stinner in bpo-39351.)