Bug with older_than and younger_than features

Hello

If my english is not clear enough, we could try in french 😉

When using older_than and younger_than options in .ini file, program raise errors

line 114, in boost_only_if_younger_than tootbirth = datetime.datetime.strptime(self.toot['created_at'].split('.')[0], '%Y-%m-%dT%H:%M:%S') AttributeError: 'datetime.datetime' object has no attribute 'split'

Little experiment show me that Mastodon.py return a datetime.datetime object in self.toot['created_at'] instead of a time string.

So, a line like this one seems to work (but I'm not very comfortable with datetime in Python).

tootbirth = self.toot['created_at'].replace(tzinfo=None)