nut/monitor: Fix tmpfs mount syntax

`dest` is not a valid option for the `--mount` argument to `podman`.  To
specify where the target path, only `target`, `destination`, and `dst`
are valid.

templates/nut/nut-monitor.container

@@ -11,7 +11,7 @@ Pull=newer
 Exec=upsmon -F
 User=nut
 RunInit=true
-Mount=type=tmpfs,dest=/run/nut,chown=true
+Mount=type=tmpfs,target=/run/nut,chown=true
 Volume=/etc/ups:/etc/ups:ro
 ReadOnly=true
 VolatileTmp=true