restic: Simplify timerConfig

The upstream restic module validates the types anyway, so I can drop the
ugly expression to copy the option.

modules/restic.nix

@@ -1,4 +1,4 @@
-{ pkgs, config, lib, options, ... }:
+{ pkgs, config, lib, ... }:
 let
   cfg = config.sbruder.restic;
 
@@ -41,20 +41,13 @@ in
 {
   options.sbruder.restic = {
     enable = lib.mkEnableOption "restic";
-    timerConfig = lib.recursiveUpdate
-      ((lib.elemAt
-        (lib.elemAt
-          options.services.restic.backups.type.getSubModules
-          0
-        ).imports
-        0)
-        { name = ""; }).options.timerConfig
-      {
-        default = {
-          OnCalendar = "20:00";
-          RandomizedDelaySec = "2h";
-        };
+    timerConfig = lib.mkOption {
+      type = with lib.types; attrsOf str;
+      default = {
+        OnCalendar = "20:00";
+        RandomizedDelaySec = "2h";
       };
+    };
     extraPaths = lib.mkOption {
       type = lib.types.listOf lib.types.str;
       default = [ ];
@@ -74,6 +67,7 @@ in
 
     services.restic.backups.system = {
       inherit repository;
+      inherit (cfg) timerConfig;
       passwordFile = config.krops.secrets.restic-password.path;
       s3CredentialsFile = config.krops.secrets.restic-s3.path;
       paths = [
@@ -87,7 +81,6 @@ in
         "--exclude-file=${excludesFile}"
         "--verbose"
       ];
-      timerConfig = cfg.timerConfig;
     };
 
     systemd.services."restic-backups-system".serviceConfig = {