go-retryablehttp VS retry-go

Both cases can be mitigated with automated retries. We went with hashicorp/go-retryablehttp as Echoes is built in Go. The library's default retry policy rightly doesn't consider a 401 response as a recoverable error, but this can be changed using the [CheckRetry hook](https://pkg.go.dev/github.com/hashicorp/go-retryablehttp#CheckRetry).

Why this instead of https://github.com/avast/retry-go or https://github.com/cenkalti/backoff ?

What is that advantage of your package compared to other ones like https://github.com/avast/retry-go?

processCreateEmail handling create email events, it's start tracing span, increase metrics counters, then unmarshal message data, and call usecase create method, if it fails, we retry for 3 times using retry-go, if it still fails, we check is the current message redelivered and if redelivery count > maxRedeliveryCount(it's up to your business logic, here is 3 times limit), handling error cases can be very different and depends on your service business logic, in this example used Dead Letter Queue approach.

Workers validate message body then call usecase, if it's returns error, try for retry, good library for retry is retry-go, if again fails, publish error message to very simple Dead Letter Queue as i said, didn't implement here any interesting business logic, so in real production we have to handle error cases in the better way. And after message success processed commit it.