await usage classes in main

Author: selfmadecode

src/SafeCrypt.Test/Program.cs

@@ -1,8 +1,8 @@
 // See https://aka.ms/new-console-template for more information
 using SafeCrypt.App.Usage;
 
-RsaUsage.Execute();
+await RsaUsage.Execute();
 
-AesUsage.Execute();
+await AesUsage.Execute();
 
-Console.ReadLine();
+Console.ReadLine();