nixos: services: use 'postgresql.target'

This is now the more correct dependency to use in service definitions,
to guarantee read-write access with users and permissions.

modules/nixos/services/tandoor-recipes/default.nix

@@ -49,8 +49,8 @@ in
 
     systemd.services = {
       tandoor-recipes = {
-        after = [ "postgresql.service" ];
-        requires = [ "postgresql.service" ];
+        after = [ "postgresql.target" ];
+        requires = [ "postgresql.target" ];
 
         serviceConfig = {
           EnvironmentFile = cfg.secretKeyFile;