unifi: update container to final revision

This is the final revision of
https://github.com/linuxserver/docker-unifi-controller

Future updates should switch to
https://github.com/linuxserver/docker-unifi-network-application

This is a pain and I'm not doing it now, it involves running mongodb
manually which is awful. Two options:
1. Switch to the new docker container.
2. Wait until NixOS natively supports a version later than 8.0.24 and
   switch to that.

modules/services/unifi.nix

@@ -40,7 +40,7 @@ in
 
     virtualisation.oci-containers.containers = {
       "unifi" = {
-        image = "lscr.io/linuxserver/unifi-controller:8.0.7-ls218";
+        image = "lscr.io/linuxserver/unifi-controller:8.0.24-ls221";
         environment = {
           PUID = toString config.ids.uids.unifi;
           PGID = toString config.ids.gids.unifi;