Tor: fix permission of /var/ipfire/tor/settings

Tor: fix permission of /var/ipfire/tor/settings

The settings file must be writeable for group "nobody" so
users can change their Tor settings via WebUI. Since other
files in /var/ipfire/tor/ does not need this workaround, only
the settings file permissions are changed.

Sorry for the late fix; this was reported by various people
in the forum, too (I was unaware of so many Tor users in our
community).

Fixes #12117

Reported-by: Erik Kapfer <erik.kapfer@ipfire.org>
Signed-off-by: Peter Müller <peter.mueller@ipfire.org>
Signed-off-by: Arne Fitzenreiter <arne_f@ipfire.org>