Middleware-level retry with exponential backoff. This is complementary to Consumer-level retry — use this when you want to retry at the middleware layer (e.g. transient DB errors) before propagating failure to the Consumer's retry logic.
Options (pass in consumer middleware list as {Retry, max: 2}):
middleware [{PhoenixMicro.Middleware.Retry, max: 2, base_delay: 100}]