pub fn pool_idle_timeout<D>(&mut self, timeout: D)
    where
        D: Into<Option<Duration>>,
    {
        self.pool_idle_timeout = timeout.into();
    }
Set an timeout for idle sockets being kept-alive.
Some AWS services, [like S3](https://aws.amazon.com/premiumsupport/knowledge-center/s3-socket-connection-timeout-error/)
require this value to match the one configured at the server's level
in order to avoid connection closed errors.
rusoto/core/src/request.rs