Fix a crash when command line tools are missing

[MrARM]

This fixes a small crash I found when I installed auto_rx on my Mac.

If gtimeout is not installed, sys.exit(1) is called from auto_rx/autorx/utils.py, and this file does not import sys. The program does exit, but not gracefully as you can see:

2025-03-31 20:25:57,728 CRITICAL:timeout command-line tool not present in system. try installing gtimeout.
Traceback (most recent call last):
  File "<...>/radiosonde_auto_rx/auto_rx/auto_rx.py", line 1102, in <module>
    main()
  File "<...>/radiosonde_auto_rx/auto_rx/auto_rx.py", line 833, in main
    if not check_rs_utils(config):
           ^^^^^^^^^^^^^^^^^^^^^^
  File "<...>/radiosonde_auto_rx/auto_rx/autorx/utils.py", line 74, in check_rs_utils
    _ = timeout_cmd()
        ^^^^^^^^^^^^^
  File "<...>/radiosonde_auto_rx/auto_rx/autorx/utils.py", line 61, in timeout_cmd
    sys.exit(1)
    ^^^
NameError: name 'sys' is not defined. Did you forget to import 'sys'
Main Loop Error - name 'sys' is not defined

This small PR adds the missing sys import, and lets the program exit gracefully.

[MrARM]

A sidenote: On mac, gtimeout can be installed through brew by installing coreutils.

[darksidelemm]

Please redirect this PR to the testing branch, and I'll merge it.

[MrARM]

Please redirect this PR to the testing branch, and I'll merge it.

Alright, I've set it to the testing branch.