src/bin/sage-venv-config: Do not fail if sage_conf is not available #31058
Description
(from #30013)
if sage_conf is not installed, because VERSION is defined there
Traceback (most recent call last):
File "/usr/bin/sage-venv-config", line 29, in <module>
_main()
File "/usr/bin/sage-venv-config", line 17, in _main
version='%(prog)s ' + VERSION)
NameError: name 'VERSION' is not defined
CC: @antonio-rojas @slel
Component: scripts
Author: Matthias Koeppe
Branch/Commit: 93a9fcf
Reviewer: Antonio Rojas
Issue created by migration from https://trac.sagemath.org/ticket/31058