fix: SubjectがNoneのときに、対取りが置き換わらないのを修正。

ついでに、インデント修正。

lambda/notice-to-slack/notice_to_slack.py

@@ -9,7 +9,9 @@ def make_attaches(event):
     for evt in event.get('Records'):
         sns_event = evt.get('Sns')
         event_subscription_arn = evt.get('EventSubscriptionArn')
-        subject = sns_event.get('Subject', 'AWS Notification Message')
+        subject = sns_event.get('Subject')
+        if subject is None:
+            subject = 'AWS Notification Message'
         sns_timestamp = sns_event.get('Timestamp')
         message = sns_event.get('Message')
         message_id = sns_event.get('MessageId')