Modernized packaging needed + Sopel 8 requirement bump

[dgw]

I can't get to all of the plugins at once, and we think this is a lesser-used one. But I intend to get to them all Eventually™ and creating an issue that I can self-assign helps with that.

(The project doesn't collect any analytics, so we have only anecdotal evidence and guesses to figure out which plugins are frequently used. Guessing is probably good enough. Probably.)