Add some pagination tests

[instantiator]

Hey there - I've been using pagination a bit when retrieving things like Notifications.

I struggled a little with the Mastodon API documentation I've found so far (in particular, the difference between minId and sinceId), so I decided to write a few small tests to help illustrate this.

I'm definitely using minId incorrectly, which is why that particular test fails. It'd be good to understand it a bit better, but in the meantime I figured you might want to add some pagination tests to your solution, to illustrate how to use it.

Feel free to borrow from what I've written if it's easier: https://github.com/instantiator/Mastonet/pull/1