MSG parsing stopped working

Let me ping @rgracia here since I found that he is the author ;)

The MSG parsing script (backend/scripts/log_parser.py) stopped working on 2021-05-05. It's related to the date formatting in Jpp which is now ISO 8601.

Anyways, it's not a big deal, but it should be fixed.

I can take it over...

See http://arca.mon.km3net.de/logs.html