New comment by sgn on void-packages repository

https://github.com/void-linux/void-packages/pull/46330#issuecomment-1741738299

Comment:
> This error looks more like an error in the test system
> 
> ```
> xcffib/testing.py:139: AssertionError
> ---------------------------- Captured stderr setup -----------------------------
> _XSERVTransSocketUNIXCreateListener: ...SocketCreateListener() failed
> _XSERVTransMakeAllCOTSServerListeners: server already running
> (EE) 
> Fatal server error:
> (EE) Cannot establish any listening sockets - Make sure an X server isn't already running(EE) 
> ```

Use `xvfb-run`