hydra: restrict starman workers to 10

modules/services/server/hydra.nix

@@ -10,6 +10,7 @@
         notificationSender = "hydra@kabtop.de";
         useSubstitutes = true;
         minimumDiskFree = 50;
+	maxServers = 10;
       };
       nix-serve = {
           enable = true;