class UpstashRatelimitHandlerCallback to handle rate limiting based on the number of requests or the number of tokens in the input.
It uses Upstash Ratelimit to track the rate limit which utilizes Upstash Redis to track the state.
Should not be passed to the chain when initializing the chain. This is because the handler has a state which should be fresh every time invoke is called. Instead, initialize and pass a handler every time you invoke.