only build for server system

flake.lock

@@ -17,15 +17,16 @@
     },
     "nixpkgs": {
       "locked": {
-        "lastModified": 1651024496,
-        "narHash": "sha256-uKSrrw/neSkxX6TXPSaMyfu7iKzFrK7F6HOt6vQefGY=",
+        "lastModified": 1650921206,
+        "narHash": "sha256-RGlfTC2ktqLVw0gBvZeCM//B4ig2CdQJm39sDvm0DBQ=",
         "owner": "NixOS",
         "repo": "nixpkgs",
-        "rev": "d9e593ed5889f3906dc72811c45bf684be8865cf",
+        "rev": "3a9e0f239d80fa134e8fcbdee4dfc793902da37e",
         "type": "github"
       },
       "original": {
         "id": "nixpkgs",
+        "ref": "nixos-21.11",
         "type": "indirect"
       }
     },

flake.nix

@@ -5,7 +5,7 @@
   };
 
   outputs = { self, nixpkgs, flake-utils }:
-    flake-utils.lib.eachDefaultSystem (system:
+    flake-utils.lib.eachSystem [ flake-utils.lib.system.x86_64-linux ] (system:
       let site = import ./default.nix { pkgs = nixpkgs.legacyPackages.${system}; };  
       in {
         hydraJobs.site = site;