Disable SetReadDeadline calls

I want to connect to Redis over SSH with golang.org/x/crypto/ssh. Currently ssh channels does not support deadlines. See https://github.com/golang/go/issues/65930.

So the following calls should be disabled.

• https://github.com/gomodule/redigo/blob/247f6c0e0a0ea200f727a5280d0d55f6bce6d2e7/redis/conn.go#L748
• https://github.com/gomodule/redigo/blob/247f6c0e0a0ea200f727a5280d0d55f6bce6d2e7/redis/conn.go#L748

Right now, there is no way we can do that.