fix memory leak

LeStorage/Utils/Date+Extensions.swift

@@ -9,19 +9,19 @@ import Foundation
 
 extension Date {
 
-    static var iso8601Formatter: ISO8601DateFormatter {
+    static var iso8601Formatter: ISO8601DateFormatter = {
         let iso8601Formatter = ISO8601DateFormatter()
         iso8601Formatter.timeZone = TimeZone(abbreviation: "CET")
         iso8601Formatter.formatOptions = [.withInternetDateTime, .withTimeZone]
         return iso8601Formatter
-    }
+    }()
     
-    public static var iso8601FractionalFormatter: ISO8601DateFormatter {
+    public static var iso8601FractionalFormatter: ISO8601DateFormatter = {
         let iso8601Formatter = ISO8601DateFormatter()
         iso8601Formatter.timeZone = TimeZone(abbreviation: "CET")
         iso8601Formatter.formatOptions = [.withInternetDateTime, .withTimeZone, .withFractionalSeconds]
         return iso8601Formatter
-    }
+    }()
     
     public static var microSecondFormatter: DateFormatter = {
         let formatter = DateFormatter()