Merge pull request #229138 from exzombie/fix/fstrim-interval

nixos/fstrim: fix overriding the timer interval

nixos/modules/services/misc/fstrim.nix

···
 
     systemd.timers.fstrim = {
       timerConfig = {
-        OnCalendar = cfg.interval;
+        OnCalendar = [ "" cfg.interval ];
       };
       wantedBy = [ "timers.target" ];
     };