fixed some warnings in data

src/data.py

@@ -1,4 +1,5 @@
 from enum import Enum
+from typing import Union
 import re
 import datetime
 import logging
@@ -87,8 +88,8 @@ class Message():
                  date: datetime.datetime,
                  user: str,
                  channel: Channel,
-                 guild: str = None,
-                 to_from: str = None) -> None:
+                 guild: Union[str, None] = None,
+                 to_from: Union[str, None] = None) -> None:
         self.message = message
         self.date = date
         self.channel = channel