Fix: qvm-ls outputs to stderr for --help-* calls

[jamke]

The problem is that ArgumentParser has no ability to provide output file for exit() calls. In the ArgumentParser documentation [1] there is even no information about output target file (stderr or stdout) for ArgumentParser.exit() functions, but from the source code of argparse [2] it is obvious that it always outputs message to stderr which is not desired in our case. [1]: https://docs.python.org/3/library/argparse.html#exiting-methods [2]: https://github.com/python/cpython/blob/3.11/Lib/argparse.py#L2612

I have tested this patch on my system, it works as expected.

Fixes QubesOS/qubes-issues#8408

[marmarek]

PipelineRetry

[codecov]

Codecov Report

Merging #254 (2cc0898) into main (4023ee2) will increase coverage by 0.28%.
Report is 4 commits behind head on main.
The diff coverage is 0.00%.

@@            Coverage Diff             @@
##             main     #254      +/-   ##
==========================================
+ Coverage   75.12%   75.40%   +0.28%     
==========================================
  Files          51       51              
  Lines        7806     8454     +648     
==========================================
+ Hits         5864     6375     +511     
- Misses       1942     2079     +137     

Files Changed	Coverage Δ
qubesadmin/tools/qvm_ls.py	80.70% <0.00%> (+2.68%)	⬆️

... and 4 files with indirect coverage changes