Fix date parsing failing due to missing field for int parsing

mastodon/Mastodon.py

@@ -2579,7 +2579,7 @@ class Mastodon:
         """
         Converts json string numerals to native python bignums.
         """
-        for key in ('id', 'week', 'in_reply_to_id', 'in_reply_to_account_id', 'logins', 'registrations', 'statuses'):
+        for key in ('id', 'week', 'in_reply_to_id', 'in_reply_to_account_id', 'logins', 'registrations', 'statuses', 'day'):
             if (key in json_object and isinstance(json_object[key], six.text_type)):
                 try:
                     json_object[key] = int(json_object[key])