Prefer `IO#wait_readable` and `IO#wait_writable` where possible.

[samuel-williams-shopify]

There are several instances of IO.select with a single file descriptor. It is better to use IO#wait_readable or IO#wait_writable` because it is more efficient internally.

ruby-kafka/lib/kafka/socket_with_timeout.rb

Line 40 in 62a0cf9

unless IO.select(nil, [@socket], nil, connect_timeout)

[dasch]

Could you create a PR for that?