Adjusting brightness only takes effect with change of current entry

[jfcloutier]

Delux.adjust_brightness/1 only takes effect when changing the current entry.

Then, https://github.com/smartrent/delux/blob/a6c10fbaaa2545030488e526da5071d8bfef408f/lib/delux.ex#L466 runs with the changed brightness.

This limitation is possibly what is meant by https://github.com/smartrent/delux/blob/a6c10fbaaa2545030488e526da5071d8bfef408f/lib/delux.ex#L165