pinwheel: Add swapfile

hosts/pinwheel/hardware-configuration.nix

@@ -36,7 +36,12 @@
     fsType = "vfat";
   };
 
-  swapDevices = [ ];
+  swapDevices = [
+    {
+      device = "/swapfile";
+      size = 24 * 1024; # 24GB
+    }
+  ];
 
   # Enables DHCP on each ethernet and wireless interface. In case of scripted networking
   # (the default) this is the recommended approach. When using systemd-networkd it's