Add timeout when connecting to server

[technicalpickles]

Over on #663 we've seen the spring server get into a funky state, where the server.gets just hangs indefinitely.

I found other places in client.rb that checked that there was something to read before reading, and made sure server.gets returns something. So, applied that to verify_server_version 😁

[technicalpickles]

I tested this two ways:

1. bin/spring start in one console. background it, and run bin/rails console (or any other binstub)
2. socat unix-listen:tmp/spring.sock /dev/null in one console. set SPRING_PIDFILE=tmp/spring.pid SPRING_SOCKET=tmp/spring.sock, and add the socat pid to tmp/spring.sock

In both, the binstub raises an error as expected.

[casperisfine]

cc @byroot

[byroot]

So note that this only tell us there's something to read, it doesn't guarantee it's a whole line, so we can still potentially get stuck in server.gets.

However it should catch a large portion of such issues, so I think it's a good improvement.

[technicalpickles]

Thank you! I'll be testing this on our app, and I'm hoping it will help surface when #663 happens