Automatic updates: restart basic daemons

By default only mcron is restarted. It was verified within the
guix-installer-vm that this change worked by looking at the pid of
guix-daemon, waiting for an automatic update to happen and looking at
the (new) pid of guix-daemon.

The mumble-server and nginx daemons were not added to the list because
we don't have the audio.experimental.a-lec.org domain setup yet in the
Libre en Communs DNS.

Signed-off-by: Denis 'GNUtoo' Carikli <GNUtoo@cyberdimension.org>

mumble-vm-system.scm.tmpl

@@ -275,7 +275,8 @@ https://DOMAIN/
         (operating-system-file (string-append "/run/current-system/profile"
                                               "/share/mumble-vm/configs/"
                                               "mumble-vm-system.scm"))
-        (schedule "30 * * * * "))))
+        (schedule "30 * * * * ")
+        (services-to-restart (list 'guix-daemon 'mcron 'ssh-daemon)))))
      (if enable-wireguard?
          (list
           (service wireguard-service-type