change the name of the auto update script

oups, run-parts (which launch cron.daily) only execute file matching this:

       If  neither the --lsbsysinit option nor the --regex option is given then the names must consist entirely of ASCII upper-
       and lower-case letters, ASCII digits, ASCII underscores, and ASCII minus-hyphens.       If  neither the --lsbsysinit option nor the --regex option is given then the names must consist entirely of ASCII upper-
       and lower-case letters, ASCII digits, ASCII underscores, and ASCII minus-hyphens.

The stupid `.sh` makes it doesn't work...