Set operation claims insufficient memory

[RealBar]

in the current version of commands.go,

func (c cmdable) Set(key string, value interface{}, expiration time.Duration) *StatusCmd {
	args := make([]interface{}, 3, 4)
...
}

is insufficient, causeing subsequent operation

args = append(args, "px", formatMs(expiration))

or

args = append(args, "ex", formatMs(expiration))

to expand the slice capacity from 4 to 8, which is an unnecessary waste.
Since this method Set is so frequently used, this small defect may cause notable performance reduction.