getmail: use attribute set to define files

To avoid warning message concerning deprecation of the `loaOf` type.

modules/programs/getmail.nix

@@ -47,14 +47,14 @@ let
   getmailEnabled = length (filter (a: a.getmail.enable) accounts) > 0;
   # Watch out! This is used by the getmail.service too!
   renderConfigFilepath = a: ".getmail/getmail${if a.primary then "rc" else a.name}";
+
 in
 
-  {
+{
   config = mkIf getmailEnabled {
-      home.file = map (a:
-        { target = renderConfigFilepath a;
-          text = renderAccountConfig a;
-        }) accounts;
-
+    home.file =
+      foldl' (a: b: a // b) {}
+      (map (a: { "${renderConfigFilepath a}".text = renderAccountConfig a; })
+      accounts);
   };
-  }
+}