The update script backs up the config file to `/root/config.bak`, but
then tries to restore it from `/root/config.yml.bak` (which obviously
won't be found).
This looks like a typo in the backup command, so update that command to
use the same filename as the restore command.
Signed-off-by: Ross Simpson <ross@rosssimpson.com>
Before:
```
bash: ./update_pwnagotchi.sh: /bin/bash^M: bad interpreter: No such file or directory
```
Thus:
```
scripts/update_pwnagotchi.sh: Bourne-Again shell script text executable, ASCII text, with CRLF line terminators
dos2unix: converting file scripts/update_pwnagotchi.sh to Unix format...
scripts/update_pwnagotchi.sh: Bourne-Again shell script text executable, ASCII text
```
Now it works :)
