No ETS cleanup?

Hi folks,

thanks a lot for the project!

In micro benchmarks the performance is truly impressive compared to other solutions.

Looking through the code, I don't think there is any cleanup of the ETS table used to store the rate limiters - am I missing something? Ideally, I think the ETS should be cleaned up - depending on what you rate limit on you might not hear from a client in a long time and so that would just get up memory consumption it feels like.