Circuit breaker for failing downstream resources

A common case is that a task queue worker issues a DDoS against a downstream resource (database, website it scrapes, ...). To reduce the impact of such event, a common pattern is to put in place is a circuit breaker.

This issue proposes to add a circuit breaker to cmdstalk. After scouring the Internet of circuit breaker libraries, I suggest using https://failsafe-go.dev/circuit-breaker/ since it has a `RemainingDelay()` method to make it easy to sleep until the circuit breaker becomes half-open again.

The issue is about adding a circuit breaker to cmdstalk, a beanstalkd broker written in Go. The suggested library is failsafe-go. Start by examining the main broker logic in cmdstalk to understand where downstream calls (like database or web scraping) are made. Look at the failsafe-go documentation for circuit breaker usage, particularly the RemainingDelay method. Determine where to integrate the breaker to wrap calls that could fail. 'Done' means the circuit breaker is integrated and tested, preventing DDoS on downstream resources.

Vom Indexierungsmodell aus dem Issue-Text verfasst.