system: move garbage collector to a separate module

don't use garbage collector on laptop yet

outputs/system.nix

@@ -7,6 +7,7 @@ with inputs;
     modules = [
       dedsec-grub-theme.nixosModule
       ../system/configuration.nix
+      ../system/garbage-collector.nix
       ../system/machine/home
     ];
   };

system/configuration.nix

@@ -124,23 +124,10 @@ in
   };
 
   virtualisation = {
-    docker = {
-      enable = true;
-      autoPrune = {
-        enable = true;
-        dates = "weekly";
-      };
-    };
+    docker.enable = true;
   };
 
   nix = {
-    # Automate garbage collection
-    gc = {
-      automatic = true;
-      dates = "weekly";
-      options = "--delete-older-than 7d";
-    };
-
     settings = {
       auto-optimise-store = true;
 

system/garbage-collector.nix

@@ -0,0 +1,14 @@
+{ ... }:
+
+{
+  nix.gc = {
+    automatic = true;
+    dates = "weekly";
+    options = "--delete-older-than 7d";
+  };
+
+  virtualisation.docker.autoPrune = {
+    enable = true;
+    dates = "weekly";
+  };
+}