Miki allows you to send marriage requests to bots

[arktn]

Describe the bug
When using >marry on a Discord bot Miki will send the proposal message but the bot can't accept the proposal (resonably so).

To Reproduce
Steps to reproduce the behavior:

1. Use >marry on a Discord bot.
2. Try to use >marriage accept trough the bot.

Expected behavior
The bot should checks if the pinged user is a bot and if so should send a different message than the proposal one. An example for this would be the message that the bot sends after trying to marry Miki itself.

Since Miki obviously doesn't react upon bot input a different message than the proposal one would be nice.