add Expiration field to Claims

Author: 2ynn

src/SpeakeasySDK/Models/Shared/Claims.cs

@@ -17,5 +17,6 @@ public class Claims
         public string? Subject { get; set; }
         public string? Issuer { get; set; }
         public string? Audience { get; set; }
+        public DateTime? Expiration { get; set; }
     }
 }