systemd: copy matterbridge restarter into gitea one

It used to stop working randomly without a good reason, but that is
likely fixed upstream a long time ago and while I removed it from cron,
these units exist so should the issue recur, I can throw these back in.

The cron wasn't randomized though, but I don't think there is harm in
this being a bit random.

etc/systemd/system/gitea-restart.service

@@ -0,0 +1,6 @@
+[Unit]
+Description=Gitea restarter
+
+[Service]
+Type=oneshot
+ExecStart=/bin/systemctl restart gitea.service --quiet

etc/systemd/system/gitea-restart.timer

@@ -0,0 +1,11 @@
+[Unit]
+Description=Execute Gitea restarter daily between 05-06 Finnish time
+
+[Timer]
+OnCalendar=*-*-* 05:00:00 Europe/Helsinki
+#OnBootSec=0
+RandomizedDelaySec=1h
+Persistent=true
+
+[Install]
+WantedBy=timers.target