SearXNG quadlet: use AddDevice= (the generator rejects Device=)

Device= in [Container] is a [Volume]-group key; the container device key is
AddDevice= (maps to podman --device). Update the /dev/net/tun device line and
the test seam.

dankclaw/searxng/quadlet/gluetun.container

@@ -18,7 +18,7 @@ ContainerName=gluetun
 Network=searxng.network
 Image=docker.io/qmcgaw/gluetun:latest
 AddCapability=NET_ADMIN
-Device=/dev/net/tun:/dev/net/tun
+AddDevice=/dev/net/tun:/dev/net/tun
 Environment=VPN_SERVICE_PROVIDER=${VPN_SERVICE_PROVIDER}
 Environment=VPN_TYPE=${VPN_TYPE}
 Environment=WIREGUARD_PRIVATE_KEY=${WIREGUARD_PRIVATE_KEY}