refactor: match current format

Todos/Controller/SaveController.swift

@@ -9,7 +9,7 @@ import Foundation
 
 final class SaveController {
   static func filename(date: String) -> URL {
-    URL.documentsDirectory.appending(path: "Todo \(date).yaml")
+    URL.documentsDirectory.appending(path: "Weekly Tracker \(date).yml")
   }
   
   static func save(_ items: [Category], to: URL) {