Function outbox_relay 

pub async fn outbox_relay<Tls>(
    pool: Pool<PostgresConnectionManager<Tls>>,
    database_url: &str,
    redpanda_host: impl Into<String>,
    slot: &str,
) -> Result<(), Error>
where
    Tls: MakeTlsConnect<Socket> + Clone + Send + Sync + 'static,
    <Tls as MakeTlsConnect<Socket>>::Stream: Send + Sync,
    <Tls as MakeTlsConnect<Socket>>::TlsConnect: Send,
    <<Tls as MakeTlsConnect<Socket>>::TlsConnect as TlsConnect<Socket>>::Future: Send,