tcp read and write timeouts

[cirocosta]

levin-related: when reading from the tcp sockets that get created for each host, we should enforce some deadlines in order to make sure the opposite of a slow-loris is taking place by a tweaked server

[cirocosta]

https://github.com/cirocosta/drwho/blob/1779a15e1f6df68fe918ec72ebc05a851e38ea23/pkg/who/whois.go#L222-L237

	elapsed := time.Since(start)
	_ = conn.SetWriteDeadline(time.Now().Add(c.timeout - elapsed))


	if _, err = conn.Write(query); err != nil {
		return nil, fmt.Errorf("write query '%s' to server '%s': %w",
			string(query), server, err)
	}


	elapsed = time.Since(start)
	_ = conn.SetReadDeadline(time.Now().Add(c.timeout - elapsed))


	buffer, err := ioutil.ReadAll(conn)
	if err != nil {
		return nil, fmt.Errorf("read response for query '%s' "+
			"on server '%s': %w", string(query), server, err)
	}

[cirocosta]

#19