fix: menubar icons in preferences handle dark mode

src/ui/preferences-window/tabs/GeneralTab.swift

@@ -9,7 +9,7 @@ class GeneralTab {
         let menubarIconDropdown = menubarIcon[1] as! NSPopUpButton
         for i in 0...2 {
             let image = NSImage.initCopy("menubar-" + String(i + 1))
-            image.isTemplate = false
+            image.isTemplate = i < 2
             menubarIconDropdown.item(at: i)!.image = image
         }
         menubarIconDropdown.item(at: 3)!.image = NSImage(size: NSSize(width: 1, height: menubarIconDropdown.item(at: 0)!.image!.size.height))