Quote variable

Co-authored-by: Christian Mäder <cimnine@users.noreply.github.com>

docker/housekeeping.sh

@@ -4,5 +4,5 @@ echo "Interval set to ${SECONDS} seconds"
 while true; do
   date
   /opt/netbox/venv/bin/python /opt/netbox/netbox/manage.py housekeeping
-  sleep ${SECONDS}s
+  sleep "${SECONDS}s"
 done