Reduce the number of default threads in the worker pool

default.nix

@@ -66,7 +66,7 @@ in
         * whenever
         Queues can be configured in different ways. Please check the good job docs for the possibilities: https://github.com/bensheldon/good_job#optimize-queues-threads-and-processes
       '';
-      default = [ "+within_30_seconds,within_5_minutes,within_30_minutes,whenever" ];
+      default = [ "+within_30_seconds,within_5_minutes,within_30_minutes,whenever:2" ];
       example = [ "within_30_seconds" "within_5_minutes:5;within_30_minutes:2;whenever:2" "+within_30_seconds,within_5_minutes,within_30_minutes,whenever" ];
       type = types.listOf types.str;
     };