nixos/unbond: unbound should be required for nss-lookup.target

Other units depend on nss-lookup.target and expect the DNS resolution to
work once that target is reached. The previous version
`wants=nss-lookup.target` made this unit require the nss-lookup.target
to be reached before this was started.

Another change that we can probalby do is drop the before relationship
with the nss-lookup.target. That might just be implied with the current
version.

nixos/modules/services/networking/unbound.nix

@@ -154,8 +154,7 @@ in
       description = "Unbound recursive Domain Name Server";
       after = [ "network.target" ];
       before = [ "nss-lookup.target" ];
-      wants = [ "nss-lookup.target" ];
-      wantedBy = [ "multi-user.target" ];
+      wantedBy = [ "multi-user.target" "nss-lookup.target" ];
 
       preStart = lib.mkIf cfg.enableRootTrustAnchor ''
         ${cfg.package}/bin/unbound-anchor -a ${rootTrustAnchorFile} || echo "Root anchor updated!"