Track Member Nickname Changes via #member_update()

[pinecat]

Hello,

I was wondering if there is any interest in having the member_update() event trigger when a user's nickname in a server is updated, not just their roles. I have a diff that adds this functionality, and I would be happy to submit a PR for it.

Alternatively, should there be a new, separate handler for this (i.e. member_nick_update())? I'd be happy to change the code I have now and submit a PR for this as well.

Is this a feature that other developers using discordrb would be interested in?

Thank you!