bug: redundant double close on PTY console socket in cmd/urunc/create.go

## Description
In `cmd/urunc/create.go`, `createUnikontainer()` dials the console Unix socket and registers two `defer` close calls on the same connection:

```go
conn, err := net.Dial("unix", consoleSocket)
if err != nil {
    return err
}
defer conn.Close()

uc, ok := conn.(*net.UnixConn)
if !ok {
    return err
}
defer uc.Close()
