BUG - Spam filter should not use image filenames

[Crambor]

Many screenshot tools, or simply copied images into the discord textbox, will have the exact same image filename as a result. We currently use filenames for spam detection which can lead to false positives, with users being unnecessarily quarantined.

The below code should be modified to use something like an image checksum for attachment comparison:

ZorakBot/src/zorak/cogs/admin/admin_automod_spam_messages.py

Lines 44 to 57 in fd16e9d

	self.records[message.author.id] = {
	"last_message": message.content if message.content != "" else message.attachments[0].filename
	, "occurrence": 1
	, "1st": {"message_id": message.id, "channel_id": message.channel.id, "file_name": message.attachments[0].filename if message.content == "" else None, "file_url": message.attachments[0].url if message.content == "" else None}
	, "2nd": {}
	, "3rd": {}
	}
	# Old speaker. We are watching you...
	else:
	# Check if the last message is the same as the new one.
	the_archive = self.records[message.author.id]
	if the_archive["last_message"] == (message.content if message.content != "" else message.attachments[0].filename):