Pattern age time math fix

rocketbot/pattern.py

@@ -4,7 +4,7 @@ to take on them.
 """
 import re
 from abc import ABCMeta, abstractmethod
-from datetime import datetime
+from datetime, timezone import datetime
 from typing import Any
 
 from discord import Message, utils as discordutils
@@ -75,7 +75,7 @@ class PatternSimpleExpression(PatternExpression):
 		if self.field == 'author.name':
 			return message.author.name
 		if self.field == 'lastmatched':
-			long_ago = datetime(year=1900, month=1, day=1, hour=0, minute=0, second=0)
+			long_ago = datetime(year=1900, month=1, day=1, hour=0, minute=0, second=0, tzinfo=timezone.utc)
 			last_matched = other_fields.get('last_matched') or long_ago
 			return message.created_at - last_matched
 		raise ValueError(f'Bad field name {self.field}')