[Compose] Update netfilter-mailcow

docker-compose.yml

@@ -419,7 +419,7 @@ services:
             - acme
 
     netfilter-mailcow:
-      image: mailcow/netfilter:1.41
+      image: mailcow/netfilter:1.42
       stop_grace_period: 30s
       depends_on:
         - dovecot-mailcow