New issue by habiloid on void-packages repository

https://github.com/void-linux/void-packages/issues/33503

Description:
### System
* xuname:   Void 5.13.19_1 x86_64-musl AuthenticAMD uptodate rF
* package:  backintime-1.2.1_3
 

### Expected behavior
Perform a backup

### Actual behavior
Traceback (most recent call last):
  File "/usr/share/backintime/common/backintime.py", line 27, in <module>
    import config
  File "/usr/share/backintime/common/config.py", line 32, in <module>
    import tools
  File "/usr/share/backintime/common/tools.py", line 1801, in <module>
    class OrderedSet(collections.MutableSet):
AttributeError: module 'collections' has no attribute 'MutableSet'

### Steps to reproduce the behavior
Run backintime